Add relative mode to EFX - the movement is relative to head's current position

I have made this pre GM - I decided that GM should affect also relative EFX if needed/requested.
It also simplified the code a bit (compared to previous version)

When no relative EFX is running, there is minimal performance overhead.

This change allows few things:

- run more effects in parallel on the same movers (e.g. pan saw and tilt saw)

- prepare the efx's in advance without regard of the actual movers' position; then adjust
the position using scene made at the venue (make some efx at home - with relative flag;
at the venue, create scenes where all your head point down/up/left/right/center; now start
e.g. center scene and an efx - the efx will point at the centre; start right scene -
the efx will move to the right, etc.)

- control efx center in runtime by assigning xyarea/sliders to pan/tilt channels and adding relative efx

NOTE: prepare efx with center at 127;127 to be neutral
Bugfix: crash in rgbmatrixeditor

- create group of fixtures, e.g 4 dimmers
- create rgb matrix e.g. full columns
- set backward direction
- save workspace
- load workspace
- edit the rgb matrix
- boom!

(on the first run through, m_previewStep is set to -1, because the m_previewMap is still empty)
Merge pull request #188 from janosvitok/rgbmatrix-crash

Bugfix: crash in rgbmatrixeditor
Spanish Translation 4.5.1
Merge pull request #190 from tornel/master

Spanish Translation 4.5.1
Improved RGB Matrix Editor layout
Virtual Console: fixed copy of Click & Go feature when cloning sliders/knobs
Function Manager: started working on folders implementation
** Switched QLC+ license to Apache 2.0 **
Updated translations
Added fixtures: Pro-Lights CromoSpot 150, Evolight Colours SL3 (thanks to Lorenzo Andreani)

Fixed Click & Go with transparent background images
Engine: Do not save RGB matrix end color if not set
Very minor code style change
Merge branch 'master' into folders
Functions Manager: moved paths in a separate column
Bump to version 4.6.0

Started to improve documentation reviewed by Michael Clements
RGB Matrix: Fixed crash on document close + some status change improvements
Merge pull request #158 from janosvitok/relative-efx

Add relative mode to EFX - the movement is relative to head's current position
First working version of folders in Function Manager

TODO: delete and all the evil cases
Merge branch 'master' into folders
4.5.1 Fr Translation corrections