Adding JS hooks for init params and runtime info

Add JS PluginHost.HOOK_PARAMS_LOADED and PluginHost.HOOK_RUNTIME_INFO_LOADED to notify when interesting info has been created/updated.

Czech translation update

Allow slashes in filter regular expressions

Match each tag separately against user filter regular expression

Each article's tag should be matched against user filter regular
expression separately. Current matching confuses when you want to match
an exact tag. You suppose to write "^tag$", bug now have to write
"(^|,)tag(,|$)" which is very inconvenient and requires knowledge about
how do you process this matching.

User's regular expressions need escaping before passing them to
preg_match()