No <hr> above formless hooks' descriptions

Fixes #81
Give a notice when a hook option name is too long

See #83
Add translation into simplified Chinese

Thanks to Jack Lee.
Don't delete wordpoints_default_points_type option

Instead, save it as an empty value. This will cause it to be autoloaded
instead of forcing an extra query on non-multisites when no default is
set.

See #76
Add the default points type option on install

This way it will get autoloaded on single sites.

See #76