Fix import statements
requested to merge umxprime/VLCKit:umxprime/fix/tvos-undefined-unreferenced-types-4-fwport into master
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.
Forward port !150 (merged)