Add "busydialogdelayms" advanced setting.

Provides control over the delay until busy dialog is shown when starting
video playback.
Added a boolean condition to identify the Raspberry Pi platform (System.Platform.Linux.RaspberryPi)
PVR: Resolve channel dummy in GUIWindowPVRTimerSettings

When using Backend channel number , use channel unique ID member instead channel number
PVR: Cosmetics in GUIWindowPVRTimerSettings
remove old unused renderer files
Disable channel icon scan when icon path is empty

XBMC checks the icon path and terminates the scan early if no path is set. This commit causes the setting to respect that.
Show values of string settings with button controls
remove unload/reload of fonts when init/destroy window, as it's not needed anymore
add infolabel Player.Filename
Only print the wayland-egl part of the detected library and not wayland-client.
Forward declare EGLNativeDisplayType.

We were incorrectly forward declaring EGLNativeWindowType instead.
HttpHeader: replace CStdString with std::string + pass data by const ref
CurlFile: don't use CStdString function with HttpHeader
HttpHeader: cosmetics + remove commented out code
HttpHeader: optimizations + rename vars for clarity
HttpHeader::GetHeader: fix: include protocol line into header
(Function not used yet)
HttpHeader::Parse: fixes: skip empty parameters + use for m_protoLine only needed part of string
HttpHeader::Clear: fix: clear m_protoLine
HttpHeader::GetHeader: refactoring
HttpHeader: use vector instead of map for storing header params, move header typedefs into HttpHeader class