[rbp] Add screenshot implementation that includes video layer

As Pi doesn't use GL for video, a screenshot only contains UI.
Need to use Pi specific function for screenshot.
First implementation of the CRenderCapture interface

RenderCapture implementation for RPi using DispmanX

Minor changes that I reverted to the repo's version

Changed snapshot taking to use g_RBP.CaptureDisplay()

Removed unused fields, and changed implementation to use the width and height parameters
Use utf8 for text pasted from the clipboard
Remove 'Go to settings' Context menu from FileManager
Dont show 'Select all' in context menu, if everything is already selected
Merge pull request #3053 from jhsrennie/paste_utf8_2

Use utf8 for text pasted from the clipboard
Merge pull request #2807 from Fice/filemanager_context_cleanup

[Context Menu] Filemanager context menu cleanup
Merge pull request #3023 from popcornmix/screenshot

[rbp] Add screenshot implementation that includes video layer
Merge pull request #3020 from brooc/master

RenderCapture implementation for RPi
[buildsys] - fix missing clean of xbmc/main/main.a
correct incorrect rebase in 381600adf4d71ea33f40f79989b5a81f32179650
[fix] settings loading of default value for CSettingAddon: parent class CSettingString already handles it correctly
[jenkins] - when determining the branch name - ignore the fetched pull requests