fixes for ofDrawGridPlane, ofDrawGrid

+ fixes issue where central axis would not be drawn when non-integer tick count specified
+ fixes ofDrawGrid API to specify stepSize and numberOfSteps rather than scale, tickNumber
+ ensures numberOfSteps be a positive integer
changelog update
Fixes #3317. Make sure that pictureSize and previewSize have same aspect ratio
Changelog entry for change to OFAndroidVideoGrabber to fix image stretching problem on some devices
Merge pull request #3318 from brinkmwj/fugfix-ofandroidvideograbber-stretching-artifacts

Bug fix for camera stretching artifacts on some Android devices
uniformized API:

loadMovie -> load
loadImage -> load
saveImage -> save
initGrabber -> setup

old methods are deprecated except in the base classes and implementations
where it's dropped completely
Merge pull request #3320 from arturoc/refactor-API

uniformize API:
Merge pull request #3316 from tgfrerer/fix-ticks+drawGridPanes

fixes for ofDrawGridPlane, ofDrawGrid
Merge branch 'master' of github.com:openframeworks/openFrameworks