Merge pull request #118 from 3rt/master

Done text instrument implementation (issue #102)
Remove some warnings
Update AUTHORS
Working on effects (issue #115). Added settings dialog class, base
widget class for settings and settings widget for custom filter.
Fix 1px border around the image (issue #112)
Added spinboxes to CustomFilterSettings widget, added creation of matrix
for filter (issue #115)
Working on filters (issue #115). Some changes in effects stucture, added
custom filter.
Added sharpen filter settings & using settings dialog.
Fixed CMakeLists
Merge remote-tracking branch 'upstream/master'
Added preview widget for filters (issue #115)
Fixed possible memmory leak in imagearea & fixed CMakeLists
Merge pull request #121 from faulknercs/master

Added custom & sharpen filters
Fix preview widget for Gaussian blur (issue #115)
Feature: resize selected zone (issue #120)
Merge branch 'master' of https://github.com/Gr1N/EasyPaint