Fix for pre,post,prelink commands , relative includes and other fixes to make it more similar to how premake gmake2 works.

[LostbBlizzard]

• Fixed defualtplatform not using defualtplatform when set.
• Fixed prebuild commands runing even when its project dependencies are not built.
• Fixed project c and c++ includes not being relative to the location property.
• Fixed project pre,post,prelink not runing in the working working directory of location property.

I havent updated forceincludes because i didn't use them in project and this pull request is a bit messy.I will fix it after this pull request.

[Jarod42]

Can you split the PR by fix?

Paths (as includedirs) from toolset should be fixed now when workspace location != project location.
pre/post build command might still be an issue though.
UTs fail, I didn't check if issue come from core or your PR.

[LostbBlizzard]

I'll spit PR when I get home. Sorry I didn't see the message till today.

[LostbBlizzard]

pull request was split

• (fixed buildcommand not haveing project working directory)[https://github.com/fixed buildcommand not haveing project working directory #39]
• (fixed includedir not being relative from the cfg.workspace.location)[https://github.com/fixed includedir not being relative from the cfg.workspace.location #38]
• (fixed missing prefix in getFileDependencies)[https://github.com/fixed missing prefix in getFileDependencies #37]
• (fixed defaultplatform not being selected when set)[https://github.com/fixed defaultplatform not being selected when set #36]

Theses one more fix but depends on fixed missing prefix in getFileDependencies see #37