Prepare for counting in statsPhase

- Add counting mode to shader
- Correct for renamed properties and for new uniforms in class
Simple counting works

Counting works, but only in on direction so far (bottom-right to top-
Necessary to add counting for the other 3 direction to get the real sum.
Add stages for saving and copying to fragment shader
Use different approach for saving

First copy results to reduced texture (with offset) --> STAGE_SAVE
Add/blend the results of previous round in another rendering pass -->
STAGE_BLEND
Save results of counting to mTexReduced
Counting works now in all 4 directions
Count area and luminance in fragment shader at the same time
Add functionality for weighted centroiding
Now use original image for counting too
Fix some bugs in the counting shader
Keep common function in a single file and prepend it to the shaders.
Add the file which contains the common functions
Add functions to pack signed shorts into rgba to common.glsl
use signed shorts for (un-)packing in centroiding stage

not tested yet
Add functions to packLongs to common.glsl
Add Functions to pack/unpack signed longs
Functions to (un-)pack (un-)signed long 24bit integers and general
cleanup
Add function to print signedLabels
Add the link to common.glsl to other Cmake-files
Add printSignedLabels