feature add read-only access to current Matrix Stack

this is a clean PR and a replacement for PR #2479.

Original PR message:

having access to the matrix stack is really useful - the canonical example would be: if you want to push a normalMatrix to the shader (calculated once per frame on the CPU, used as a const many many times on the GPU):

	ofMatrix4x4 modelViewMatrix = ofGetGLProgrammableRenderer()->getCurrentMatrix(OF_MATRIX_MODELVIEW);
	ofMatrix4x4 normalMatrix = ofMatrix4x4::getTransposedOf(modelViewMatrix.getInverse());
	mShd1.setUniformMatrix4f("normalMatrix", normalMatrix);

Otherwise, you'd have to calculate the normal matrix in the vertex shader (per-vertex) or even in the fragment shader (per pixel!):

	mat4 normalMatrix = transpose(inverse(modelViewMatrix));

Matrix inverses are amongst the most costly GLSL operations.

Signed-off-by: tgfrerer <tim@poniesandlight.co.uk>
add ofGetCurrentMatrix

* adds getCurrentMatrix to ofBaseRenderer and all its direct heirs

* adds ofGetCurrentMatrix which will return the current matrix state

* this will, in order not to over-optimise the code, return an ofMatrix4x4 by copy instead of a const ofMatrix4x4 & - I trust modern compilers will automatically move these things and find the code easier to optimise this way anyway.

Signed-off-by: tgfrerer <tim@poniesandlight.co.uk>
add changelog entry

adds changelog entry for ofGetCurrentMatrix, since this affects core API

Signed-off-by: tgfrerer <tim@poniesandlight.co.uk>
use correct audio category for routing audio to speaker
closes #2100
ofAppAndroidWindow: unzip library not needed anymore
Bug fixed,Compile error in ofxAndroidSoundPlayer

Bug fixed,Compile error in ofxAndroidSoundPlayer
Modify ofVbo bind method to allow 2d vertices

Currently ofVbo bind method always sets number of components in vertex position data to 3. Fix to set number of components to either 2 or 3 based on numCoords argument to setVertexData call when passing in pointer to float array of vertices.
android: change app directory detection method
Android assets fix.
Zip file uses lowercase package name.
Doxygen config
On Windows/MinGW the value of $(PWD) is not always set to the correct "pwd" value.

In a few cases it is set to a Windows style path (C:\openFrameworks\apps\devApps\VboExample) instead of a Unix style (/c/openFrameworks/apps/devApps/VboExample) one. This results into errors when building the project and zipping the assets.
ofBaseApp: remove mouseReleased(void) - the variant with x/y/button params is always called anyway, so this one was essentially unused and confusing.

fixes #2668
ofMath: remove ofAngleSumRadians. Closes #2747
Changes to ofGstVideo files to compile with 0.10 gstreamer and fixup file names in Win32.
Merge remote-tracking branch 'origin/master-openframeworks' into master-Graham