update to .NET 4.0
Migrate to System.Lazy.
Merge pull request #5082 from pchote/dotnetfour

Upgrade to .NET 4.0
Merge pull request #5086 from ScottNZ/balance

More RA balance tweaks
clean up after MonoDevelop/Visual Studio
Update INSTALL

* .NET 4.0 #5082
* SDL 2 #3315
* avoid trademarks
Update INSTALL

we now require a .NET 4.0 compatible compiler
Minor explosion weapon sound fixes
Adds Explode weapons for ships and submarines
Adds visible explosions to ships and submarines
Adds Explosions to all vehicles that didn't have one.
fixed Dune 2000 powerdown cursor palette
don't play crumble sound when placing concrete
add the beacon button artwork to RA, D2k and TS

thanks to @xanax
Fix stupid typo, use UnitExplodeSubmarine for MSUB.
Fix typos in vehicles.yaml
Merge pull request #5091 from reaperrr/ra-vehicle-explosions

Add RA vehicle explosions
Fixes #5077
Fixed #3826
Upgrade to SDL 2.0.3 and latest SDL2-CS (e8731ef).
Fix a visual glitch in OSX.