Fix PM count caching.

cache::get() returns null if the key wasn't found (at least when using
the Redis cache backend).
pm_snippet() should probably use mb_substr if it's using mb_strlen.
Fix openBoard and boardTitle functions using same caching keys.

Added getBoardInfo function that's used by both of the above functions,
and can get a board's info without loading it.
Fix result page after installing theme getting doubled up.
Fix broken entity removal in post truncation.
mod.php: Don't freak out if extra dummy query parameters are added.
(Such as for cache-avoidance.)
Include non-compiled javascript in page.html too.
Don't forget secure tripcode that's preceded by a space.

Mod capcodes are not remembered in the posting form.
Fix "Undefined index: sticky" and "locked" errors on new thread creation.
m and n dash fix
Fix #71.
Merge pull request #115 from Macil/miscfixes

Miscellaneous fixes