parser: move prettyformat() function from revset module I want to use it in doctests that I'll add by future patches. Also, it can be used in "hg debugfileset" command.

fileset: move validation of incomplete parsing to parse() function fileset.parse() should be responsible for all parsing errors as well.

revset: move validation of incomplete parsing to parse() function revset.parse() should be responsible for all parsing errors. Perhaps it wasn't because 'revset.parse' was not a real function when the validation code was added at ffcb7e4d719f.