convert: use splicemap entries when sorting revisions (issue1748) When sorting revisions before converting them, we have to edit the revision graph using splicemap entries. Otherwise, a spliced revision may be converted before its synthetic parents. Invalid splicemap revisions are now detected before starting the conversion.

convert: turn splicemap into a simple dictionary Parsing the splicemap as a mapfile was a pain because map does not let us override its parsing code and splicemap entries are not key/values. Besides we had no need for mapfiles extra features. Just parse the splicemap and return a dictionary.

debugrevspec: mention --verbose to print the parsed tree

largefiles: only cache largefiles in new heads This fixes a serious performance regression in largefiles introduced in Mercurial 2.1. Caching new largefiles on pull is necessary, because otherwise largefiles will be missing (and unable to be downloaded) when the user tries to merge or rebase a new head with an old one. But this is an expensive operation and should only be done for heads that are new from the pull, rather than on all heads in the repository.