Mod Page Improvements

[elexis]

The mod selection page currently doesn't validate mods and the page can benefit from a number of improvements:

Implementable features:

• Drop _ and - from mod versions ​Phab:D1094
  
• Drop mod types ​Phab:D1082
  
• Add documentation, validation, validation test: ​Phab:D1093
  
• Translate mod title and description: ​Phab:D1083
  
• Visit URL button
  
• Arrow icons and Disable button ​Phab:D1079
  
• Disable save button if there are no changes
  
• Mod version label property ​Phab:D1080
  
• Rename modmod to modselection ​Phab:D1095
• Sort mods by dependency (topologic sort)
  
• Save mod version in replays and savegames #4887

Previous improvements:

In r15677:
Add mod selection mod

In r16736:
hotkey.cancel mapped to the Escape key

In r20195:
white text

In r20550:
Doubleclick lists, refs #3574 / rP17274.
Filter while typing, refs D860 / rP20091.

In r20555:
Replace mod selection sorting choice dropdown and checkbox with the column based sorting from rP16781, refs #2405.