loadable_aut: add DumpToAutDesc() and modify the core classes
explicit_tree_aut: add DumpToAutDesc() methods
explicit_tree_aut_core: change the copy constructor to be selective
explicit_tree_aut_core: add TranslateSymbols()
explicit_tree_aut: add TranslateSymbols()
explicit_tree_aut_test: add tests of TranslateSymbol()
explicit_tree_aut: add virtual destructor for AbstractAlphabet()
loadable_aut: fix DumpToAutDesc()
src/timbuk.y: downgrade requirements to bison 2.7.1
Merge remote-tracking branch 'upstream/master'