convert: when converting from Perforce use original local encoding by default On Windows Perforce command line client uses default system locale to encode output. Using 'latin_1' causes locale-specific characters to be replaced with question marks. With this patch we will use default locale by default whilst allowing to specify it explicity with 'convert.p4.encoding' config option. This is a potentially breaking change for any scripts relying on output treated as in 'latin_1' encoding. Also because hgext.convert.convcmd overwrites detected default system locale with UTF-8 we had to introduce an import cycle in hgext.convert.p4 to retrieve originally detected encoding from hgext.convert.convcmd.