[WIN32] Peripherals: clarification of iMON setting.
[cosmetics] convert tabs to space for consistency
extend metada.xsd with optional elements
set library attribute as required
add Player.IsInternetStream Infolabel
Merge pull request #2676 from ace20022/interfaces_cleanup

[Interfaces] Clean up things found by Cppcheck
Merge pull request #2670 from Karlson2k/imon_small_fix01

[WIN32] Peripherals: clarification of iMON setting
Merge pull request #2663 from MartijnKaijser/xsd

[addons] update addon XSD files to reflect latest additions
Merge pull request #2659 from herrnst/isinternetstream

add Player.IsInternetStream Infolabel
**RFC**  Possible null pointer dereference: control - otherwise it is redundant to check it against null.
[Settings] Initialize members in constructors.
**RFC** Why not initialize it in the ctor?
[Settings] Remove unused variables.
[Settings] Operator=' should return &.
[Settings] Function parameter '...' should be passed by reference.
[Settings] Prefer prefix ++/-- operators for non-primitive types.
[Settings] Possible inefficient checking for 'settingMap' emptiness.