[Opensim-dev] Raise minimum mono version to 2.6

[Justin Clark-Casey]

Whilst writing JsonStore regression tests this evening, I hit the problem where modInvoke script methods of more than 4 
parameters cannot be registered on Mono 2.4.3 as it doesn't implement the required larger multi-parameter Func generic 
types.

Therefore, I want to bump the minimum Mono version for OpenSimulator up to 2.6 which was released more than 3 years ago. 
  This also involves bumping the minimum .net framework version up to 4.0, as also detailed at [1]

[1] http://opensimulator.org/mantis/view.php?id=5971

Any comments?

-- 
Justin Clark-Casey (justincc)
OSVW Consulting
http://justincc.org
http://twitter.com/justincc