use hoedown for fenced code support
add changes
add parent.pm
upgrade module version
Renamed encoding to default_encoding

no functionality change. this is just code clean-up.
Supported specific character encoding of source code

Added new config parameter 'encoding_suspects' to put suspects encoding list.
commit diff, normal blob and blame are converted by Encode::Guess with suspects encoding list.
fix bug that dispaly blog image line number
add encoding_suspects test
add changes
add the way to merge other user branch to network/graph page