Add markdown plugin files

1. new PathResolve class
2. add markdown plugin files
Add plugin framework
bug fix: editor command not trigger modified state of webkit
Add LICENSE
update to 2.0.59
update build
update README
bug fix: cursor reset when autosave document
bug fix: fcitx input method preediting flick issue
bug fix: elid text for documents hint
update to 2.0.62
i18n TW translations
update build
Merge pull request #175 from wizardlancet/master

i18n TW translations
Merge branch 'master' into plugins
Fix build issue
Add plugin dialog and use XDG spec setting path
build on osx
critical bug fix: saving while switching

rewrite saving and loading thread to avoid saving while switch document
may cover switched document issue.
add hellworld plugin template