Neuronexus 4 shank 2 tetrode silicon probe map

* Updated images for collapse/show button;
* Updated animations;
* Some other small UI improvements;
* Added possibility to collapse element by clicking "ESC" key
  either on the component itself or on the TextEditor.

* Created SlicerChannelSelectorComponent class which holds inside
  all ChannelSelector's parser related components and which
  takes responsibility for parsing selected range, etc.
* Added possibility to collapse parser related components.
* Added animations.
* UI improvements.
* Minor bugs fixes.

* Implemented sliders' material lookAndFeel;
* Material lookAndFeel have been applied to sliders;
* Improved UI layout for panel.
* Adjusted positioning of elements during resizing.
* New icon for "Mute" button;

added functions to network module to retrieve acquisition/recording status and the current recording path

- Sync signal, wired to BNC out with the update rhd2000.bit, can be set
  to a multiple of the sample clk period using the RHD2000Editor
- This commit corresponds to this pull request:
  https://github.com/open-ephys/rhythm/pull/11

Fixed bug in NetworkEvents::createZmqContext.  Added Python example script for sending network events.

Included unistd.h for successful Linux compile, known fix from https://github.com/open-ephys/GUI/pull/150

0MQ is included, but not linked (unless you define it in
NetworkEvents.h).
Redrawing events are not called for some reason.