Issue title: Rikai can't parse 蝃蝀 
 Issue body: It might have something to do with the obscurity of the kanji

See https://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&e=2000725
 Comments: 
 Comment 0: It looks like it has to do with that being in JMdict but not EDICT. That should be fixed when rikaichamp switches to JMdict (should happen in July, I expect).
 Comment 1: That is, if I download `http://ftp.monash.edu/pub/nihongo/edict.gz` and dig into it, it has only the following entry:

```
ていとう /(n) (obsc) (arch) rainbow/
```
 Comment 2: Was that an oversight of the folks running JMdict?
 Comment 3: No idea. There's a bunch of information that gets dropped when generating the edict format (e.g. non-English glosses) so it might be intentional.
 Comment 4: Is this the same reason the addon can't read the kanji 𠏹 in 𠏹沢?
 Comment 5: @picsi 
The dictionary is distributed in three different formats: EDICT, EDICT2 and JMdict. In addition to differences in their structure, they use different character sets and encodings.

- EDICT: JIS X 0208 inside EUC-JP
- EDICT2: JIS X 0208 and JIS X 0212 inside EUC-JP
- JMdict: Unicode inside UTF-8

Rikaichamp uses EDICT, and JIS X 0208 doesn't include 蝃 or 蝀.

𠏹沢 would be supported by both JIS X 0212 and Unicode, but it doesn't have an entry in the dictionary.

http://www.edrdg.org/jmdict/edict_doc.html
 Comment 6: For what it's worth, as of version 0.1.2 Rikaichamp now uses the original kanjidic UTF-8 sources (along with quite a number of other source data files) and hence can recognize the kanji for 蝃蝀.

I'll work on switching to JMdict sources for the word dictionary next but it will take a few more weeks.
 Comment 7: @siikamiika 𠏹沢 is actually in JMnedict, but I don't know if that is distributed inside JMdict.

See https://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&q=5005893.2
 Comment 8: @picsi 
ENAMDICT/JMnedict is a different dictionary, but ENAMDICT seems to be bundled with Rikaichamp too: https://raw.githubusercontent.com/birtles/rikaichamp/master/data/names.dat (**warning; 30 MB file**)

𠏹 won't be included in ENAMDICT for the same reasons as 蝃 and 蝀 won't be in EDICT.

```
> rg ほとけ沢
enamdict
5997:ほとけ沢 [ほとけさわ] /(p) Hotokesawa/

JMnedict.xml
68205:<keb>ほとけ沢</keb>

> rg 𠏹沢
JMnedict.xml
68208:<keb>𠏹沢</keb>
```

In addition, 𠏹 is represented using surrogate pairs in Javascript due to its high code point in Unicode, so it will require special handling with length checks. Here are a few workarounds:

```javascript
const text = '𠏹';

// bad
text.length
2
// good
Array.from(text).length
1

// bad
for (let i = 0; i < text.length; i++) { console.log(text[i], i); }
� 0
� 1
// good
for (const c of text) { console.log(c); }
𠏹

// bad
text.charCodeAt(0)
55360
// good
text.codePointAt(0)
132089
```

https://www.edrdg.org/enamdict/enamdict_doc.html
 Comment 9: I'm working on switching the name dictionary sources over too, but it's currently blocked on getting the new IndexedDB-based setup to work while Firefox is in "Always on Private Browsing" mode (#148), which is going to be a bit of work.
 Comment 10:  印鑑 is also not recognized by rikaichamp but recognized by jisho.org which lists jmdict as a source: http://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&e=15829
 Comment 11: Thank you for the report! That's very odd. I will look into it on Tuesday.
 Comment 12: > 
> 
> 印鑑 is also not recognized by rikaichamp but recognized by jisho.org which lists jmdict as a source: http://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&e=15829

When I hover on the kana "いんかん", there is no corresponding kanji entry written as 印鑑 appearing in the popup.
 Comment 13: > When I hover on the kana "いんかん", there is no corresponding kanji entry written as 印鑑 appearing in the popup.

Yes, it's not in the rikaichamp joeljohnson@example.net. Nor is 印鑑証明. However 印鑑レス is, which is odd. There seems to be a bug in the job that runs to extract the JMdict data and merge it with other data (like pitch accent data). I'll look into it tomorrow or Tuesday.
 Comment 14: Got a bit nerd-sniped on this. Turns out 印鑑 is in the rikaichamp upstream database so the bug must be in the step where we generate the JSON diffs. 𠏹沢 is also in the upstream database but is also possibly not being exported correctly.

On the upside, Rikaichamp now correctly recognizes 蝃蝀 so we can close this issue once I work out what is going on with 印鑑 etc..
 Comment 15: I dug into this a bit further today and it seems like there is at least one gap in the set of records we export. It might be something to do with the way I was using DynamoDB (perhaps even an eventual consistency issue?). This will take a bit of time to debug.
 Comment 16: I've made a bunch of changes that should address all the cases in this issue. In particular, the next release of Rikaichamp should recognize:

* 印鑑
* 𠏹沢
* 𠏹

Furthermore, it should show the name preview for ほとけ沢.
 Comment 17: 逸材 is not recognized either, even though it is in EDICT. Is this something similar?
 Comment 18: > 逸材 is not recognized either, even though it is in EDICT. Is this something similar?

Works for me. Are you on 0.3.2?

![image](https://user-images.githubusercontent.com/1232595/100974576-da07e000-357f-11eb-8252-77e27c89e645.png)
 Comment 19: Looks like 逸材 was one of the words that was missing but was re-added in 7a0121dbb4993bea69de9feb825ddb0b681faf97
 Comment 20: Not working for 𡱖
 Comment 21: > Not working for 𡱖

Yeah, it looks like I messed up the range for CJK Unified Ideographs Extension B. It should include this.
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