ENH: Add some features like R data.table's fread() function.
#### Is your feature request related to a problem?

The fread() function in R library data.table has many features which are very usefull.

#### Describe the solution you'd like
### 1. An argument treat tables with untidy columns
If we get a CSV file with shorter header line than table content, just like:
>A,B,C
>a,1,123,5,6
>b,123,3,3
>c,123,555,123  

By using "fill = TRUE", we can easily read it into R:
```
library(data.table)

df1 <- fread("test.csv", sep = ",", header = TRUE, fill = TRUE)
print.data.frame(df1)

  A   B   C  V4 V5
1 a   1 123   5  6
2 b 123   3   3 NA
3 c 123 555 123 NA
```

### 2. An argument skip to one line with particular pattern

If we get an VCF file just like this:
>##fileformat=VCFv4.2
>##FILTER=<ID=Bias,Description="Strand Bias">
>##FILTER=<ID=Cluster0bp,Description="Two somatic variants are within 0 bp">
>##FILTER=<ID=DIFF0.05,Description="Non-somatic or LOH and allele frequency difference < 0.05">
>##FILTER=<ID=InDelLikely,Description="Likely Indels are not considered somatic">
>#CHROM	POS	ID	REF	ALT	QUAL	FILTER	INFO
>chr2	79314684	.	G	C	154.0	PASS	AC=3;AF=0.273;AN=11;DP=146;SOMATIC
>chr2	119750833	.	G	T	165.0	PASS	AC=3;AF=0.273;AN=11;DP=149;SOMATIC
>chr2	203964409	.	G	A	89.0	PASS	AC=2;AF=0.250;AN=8;DP=137

By using "skip = "#CHROM"", fread() can search the whole file, and jump to the first line with the pattern "#CHROM",     
and read it into R:  
```
library(data.table)

df2 <- fread("test.vcf", skip = "#CHROM")
print.data.frame(df2)

  #CHROM       POS ID REF ALT QUAL FILTER                               INFO
1   chr2  79314684  .   G   C  154   PASS AC=3;AF=0.273;AN=11;DP=146;SOMATIC
2   chr2 119750833  .   G   T  165   PASS AC=3;AF=0.273;AN=11;DP=149;SOMATIC
3   chr2 203964409  .   G   A   89   PASS          AC=2;AF=0.250;AN=8;DP=137
```
#### API breaking implications

[this should provide a description of how this feature will affect the API]

#### Describe alternatives you've considered

[this should provide a description of any alternative solutions or features you've considered]

#### Additional context

[add any other context, code examples, or references to existing implementations about the feature request here]

```python
# Your code here, if applicable

```
