GUIWindowPVR: don't spawn dedicated thread just to invalidate channel items every 5 seconds. Instead run CStopWatch when activating channel window, check if 5 seconds elapsed and then inavlidate window and reset watch.
[WIN32] Peripherals: clarification of iMON setting.
[cosmetics] convert tabs to space for consistency
extend metada.xsd with optional elements
set library attribute as required
[Interfaces] Performance: prefer prefix ++/-- operators for non-primitive types.
[Interfaces] Performance: possible inefficient checking for container emptiness.
Adjust RunSlideShow() param order.
Add 'ShowPicture()' builtin function to display single picture.
add Player.IsInternetStream Infolabel
Fix crash when audio encoder is not initalized.

In some cases, audio encoder is not initalized (as explained in ticket #14298).
[Interfaces] Performance: Returning the result of c_str() in a function that returns std::string is slow and redundant.
[PlayList] Performance: Variable 'pos' is reassigned a value before the old one has been used.
[AddonClass] Make AddonClass really non-copyable.
[Interfaces] Initialize members in constructors.
[Interfaces] Reduce the scope of variables.
[Interfaces] Remove unused variables and reduce scope in one case.
Merge pull request #2676 from ace20022/interfaces_cleanup

[Interfaces] Clean up things found by Cppcheck
[win32] Prevent crash on startup
Merge pull request #2670 from Karlson2k/imon_small_fix01

[WIN32] Peripherals: clarification of iMON setting