Const-correcting accessors in ofVbo/ofVboMesh.

This prevents ofVboMesh from being required
to override the virtual base functions in ofMesh
thus, preventing lots of warnings when using 
makefiles on osx.
Const-correcting two accessors in ofxOscMessage.
Merge pull request #1936 from bakercp/warningfix-ofVbo

Const-correcting accessors in ofVbo/ofVboMesh/ofxOscMessage
makefiles linux 32bit: fix platform detection. Closes 1938
compileOF.sh: fix permission change directory
compileOF.sh: remove obj from chown
Merge pull request #1939 from arturoc/bugfix-makefiles386

makefiles linux 32bit: fix platform detection. Closes 1938