layouts: pull out code for detecting layout from subversion This is the start of an effort to refactor the code for how we handle subversion layoout to mercurial layout mapping. Specifically, it pulls out the logic for guessing what layout to use based on the contents of subversion. It also sets up a bit of the structure for the new library.

include Makefile hgsubversion/help/*.rst
recursive-include tests *.py *.sh *.svndump *.txt