Improved Show manager show event. Much faster now

Temporarily disabled workaround for sequences switchFunction. TODO!
Fixed fast stop/start of a function with the same ID (including fade setting)

Reduced CPU usage of audio renderer thread
Use specified duration in Efx preview
Remove parameter 'direction' - replace it with efx's own direction().
Add unit tests for backward direction.

The backward path is not an exact copy of the forward path due to rounding,
but it's good enough for now.
Take effect's direction in account.

Now both EFX::direction() and EFXFixture::direction() are considered.
EFXFixture::direction() is relative its EFX's direction().

That means if both are Backward, it is the same as if they both were
Forward.

Until now, only EFXFixture::direction() was used for the movements.
Remove unused return value
Display fixture positions in the EFX preview.

- probably works with low fixture count (<9)
- only the lowest number for each direction is displayed
Add start offset to EFX.

Start offset allows to start the movement in any point of the path and complements the rotation parameter
for asymmetric patterns.
Merge pull request #114 from hfanieng/master

1 new, 1 updated fixture - updated translations
Merge pull request #117 from janosvitok/efx-improvements

Improvements to EFX module. Added start offset, updated documentation
Fixed Scene unit test

Updated changelog
Fixed Show Manager vertical resize when adding a big number of tracks

Fixed Eurolite LED-Z-200-TCL RGB channels
Resized efx screenshots properly
Updated translations (only fixtureeditor and qlcplus have new ones)
Virtual Console Frame new options: show/hide header, title font/color, set title with double click

Increased show list combo box size
Added "Hold" parameter to Chaser steps, between FadeIn and FadeOut

Fade is no more applied to Pan, Tilt and Speed channels
Added fixture: American DJ Vizi Beam 5R (thanks to Daniel Sevelt)
Added Doc modified to frame collapse event
Added stop event from Show to release connected VC buttons
Updated VC Frame docs
Sequence items in Show Manager now highlight the selected Sequence step

Fixed Show Manager horizontal track dividers position and Z value
clear ordered groups array when closing a project (thanks to Jano Svitok)
Added fixture: Martin MAC 101 (thanks to Daniel Sevelt)

Added fixture: Lanta Orion Link V2 (thanks to OddSocks)