physfs compilation on windows
* external calls must always be named
* physfs has to be compiled as dll
* there shouln't be external variables, implemented a function that sets buffer
* physfs extras is now integrated in main physfs
* removed physfs extras
[patterns]
**.h = native
**.c = native
**.cpp = native
**.lua = native
**.txt = native
**.pas = native
**.inc = native
**.hs = native