added smooth.bat for starting smooth tool on windows OS
renamed src/sh -> src/script
extracted SmoothConstants class with DEFAULT_SCRIPT and BUILD_DIR
added RecursiveDirectoryDeleter
refactored TestCaseWithTempDir to use RecursiveDirectoryDeleter
fixed TestCaseWithTempDirTest so it correctly removes temporary files needed for testing
added MemoryElement.parent()
refactored MemoryFileSystemTest
added FileSystem.deleteDirectoryRecursively()
fixed MemoryFileSystem to throw proper exceptions
refactored TestingStreamTest
refactored TestingFileSystem
renamed Files -> FileList, the same for friends
added Cleaner
reused Cleaner in SmoothRunner
refactored ArgumentsCreator, PluginInvoker