refactored out Unzipper out of UnzipFunction
added UnzipperTest, refactored UnzipFunctionTest
refactored UnzipperTest
Unzipper throws exception when finds two files with the same path
Unzipper fails when zip file contains entry with illegal filename
moved errors/exceptions classes from .builtin.compress -> builtin.compress.err package
style fix
refactored out Unjarer from UnjarFunction, added handling duplicate file names, and illegal paths
added missing UnjarFunctionTest, UnjarerTest
extracted BUFFER_SIZE constant