Issue title: Convert TODO txt file to issues
 Issue body: As I am really keen on contributing to this project I asked myself why some major issues are defined inside a To-Do txt file.
Wouldn't it be more convenient to create seperate issues from that?
 Comments: 
 Comment 0: Sure, good idea.
 Comment 1: There is also this: [document on the forum](http://forum.freeciv.org/f/viewtopic.php?f=24&t=75582&sid=4a4abea9b9333ed45e19eb604aeb91d4)
 Comment 2: Well ok this excel document has priorities.
But one place where every existing issue is listed (and perhaps sorted by labels and milestones) would be great.
{'source': 'GithubIssues', 'repo_name_with_owner': 'freeciv/freeciv-web', 'issue_id': 249800414, 'repo_stars': 1900.0}