(c backend) Use extractLibraries() method
(llvm backend) Use extractLibraries() method
(hmpp) Use extractLibraries() method
(promela) Use extractLibraries() method
(tta) Use extractLibraries() method
DAL and HLS backends doesn't need to export libraries

But since they extends C Backend, they need to override the
extractLibraries() method
(backends) Remove useless exportRuntimeLibrary() from AbstractBackends
(tta) Move runtime files under a folder with the right name

This is mandatory to use the extract() method from new
FilesManager class
(backends) Remove useless methods from AbstractBackend

copyFileToFilesystem() and copyFolderToFileSystem() have been removed.
Improved methods from FilesManager class can be used instead.
Merge branch 'backends_uniformization'