Copy mod .mdb symbol file together with .dll

Allows for MonoDevelop to debug execution in mod library properly.
Remove unused usings and arguments
Improved download progress formatting
Add cloak detection abilities to all ra defenses
(not hbox because it already has cloak detection)
Remove C4 target type from ra vehicles - Tanya was a bit too strong C4ing vehicles
Hind and Longbow were a bit too tanky, so reduced their HP levels from 150 to 100 and 150 to 120 respectively.
Increase prices of yak and hind from $1000 to $1350 (Implicit build time increase as well).
Double projectile speed of AA gun so it misses less often
Remove MustBeDestroyed from cnc support structures
Remove MustBeDestroyed from ra support structures
Add stats button to end game dialog

Also adds the statistics window to TD.  There is no button for it in
observer mode, though, but it is available from the end game dialog.

Fixes #6312.
Rename widgets
Merge pull request #6392 from ingemaradahl/debug-symbols

Copy mod .mdb symbol file together with .dll
Merge pull request #6397 from obrakmann/cnc-stats

Enable viewing game stats after the game ends
Merge pull request #6399 from DeadlySurprise/dlPolish

Fixes #6186
Merge pull request #6414 from ScottNZ/balance

Some RA balance work