Fix import statements

Many quotation mark imports have been replaced with angle brackets to fix Xcode editor issues with tvOS target.
Some imports in header files were also replaced by forward declarations.
Moreover some tvOS platform specific macros has been added to fix compilation issues introduced with these changes.

Closes #594 (closed)

assigned to @umxprime

added Maintenance label

approved this merge request

merged

Needs forward-port to master.

mentioned in merge request !155 (merged)

mentioned in commit c7f4789d

mentioned in issue #594 (closed)