Fix wrongly used CFile::Exists() for directories instead of CDirectory::Exists()
Currently it can cause hardly detectable errors as some VFS don't return true when directory is requested for CFile. One of VFS of such kind is Win32File.
Merge pull request #5349 from Karlson2k/vfs_fix_exists_01

Fix wrongly used CFile::Exists() for directories instead of CDirectory::Exists()
fixed: use the proper make instead of calling 'make' directly

fixes builds on freebsd
cmake buildsystem
add tests needed by new u16 string stuff
wrap cmyth properly
move some more install related stuff to install script
move all install code to platform install script
allow building without doxygen
fix building with yajl2
generate scripts in a subdir to avoid problems configuring in top dir
properly wrap library.xbmc.foo
link to threading lib
remove duplicate mpeg2 entry
properly locate java and swig

also use the detected paths for java, swig and doxygen
cosmetics: move all depends together for better readability
changed: build with a prefix to avoid cluttering the build dir

some peeps still do in-source builds out of old habits. this is
to annoy them slightly less, though they should STOP doing in-source
builds in the first place
grm
changed: patch libdvdnav to allow our usage of internal headers

also removes internal duped+patched headers
fixed: config.h has nothing to do outside the dvdnav build tree

though we are using internal headers, we do NOT want to set this
fixed properly through patchery