Close file descriptors and fix OpenAL issue

unloadSound() did not previously close file descriptors which would eventually lead to a crash when too many file descriptors where open (about 1000 for Raspberry Pi).

OpenAL sources must be deleted before buffers otherwise it will result in **Illegal Operation**.
ofPixels: fix iterators syntax in vs2012
Merge branch 'master' of github.com:openframeworks/openFrameworks
Merge pull request #3172 from wronex/patch-1

Close file descriptors and fix OpenAL issue
fix deprecation msg in ofShader

use iterators instead of deprecated ofBuffer line methods
Fixed numerous issues and added locking

Added thread locking, fixed getPosition, setPosition, unloadSound and proper OpenAL error fetching.
add half float gl types

adds support for 16 bit GL channels to ofGLUtils
Merge pull request #3174 from tgfrerer/fix-ofShader-deprecation-msg

fix deprecation warning in ofShader
ofShader: fix for unordered_map on visual studio
ofBuffer: remove unimplemented method
Merge branch 'master' of github.com:openframeworks/openFrameworks
Merge pull request #3175 from wronex/patch-2

Fixed numerous issues and added locking
Merge pull request #3176 from tgfrerer/add-half-float-gl-types

add half float gl type support to ofGLUtils
add mat3 uniform setter in ofShader
add note recommending 4x4 mat for shader uniform
ofShader: correct check for c++11
Merge branch 'master' of github.com:openframeworks/openFrameworks
adds some missing image types to ofGLUtils

adds some missing integer / unsigned integer formats, half-float data types
Merge pull request #3180 from tgfrerer/add-gl-image-types-to-ofGLUtils

adds some missing image types to ofGLUtils
organize includes
ofSerial: avoid warnings in unused platforms