add Global Option '--config' to specify config file insted of using _config.yml
Merge pull request #436 from chenall/dev

add Global Option '--config' to specify config file insted of using _config.yml
Update comments. Fix #432
Remove language prefix of code blocks #438
Remove prefixing and trailing line breaks in code blocks #443
Fix dots escaped in the arguments of tag plugins #444
2.4.5 release
Merge branch 'dev'