/linecount: Support new search syntax
/linecount: Support new search syntax

This brings it to the same syntax as modlog, which means you can make more varied searches while also getting defaults on values. Before, if you wanted to search a user, you had to enter everything. Now, you can just /linecount user=mia, for example.

xfix/Pokemon-Showdown,xfix/Pokemon-Showdown,xfix/Pokemon-Showdown,xfix/Pokemon-Showdown,svivian/Pokemon-Showdown,svivian/Pokemon-Showdown,svivian/Pokemon-Showdown,xfix/Pokemon-Showdown,svivian/Pokemon-Showdown,svivian/Pokemon-Showdown