[dwm] using bitaray for tags (PATCH)

Hi,

This is realization of Gottox's proposal discuted on IRC today.
It handles tags not as Bool [], but as bit-array saved in int.

There's only one problem, as I don't find easy solution (in compile time)
for check if there's no more tags than sizeof(int)*8.

Maybe it can be "asserted" with someting like (possibly global, compiler
take it away as it's not used anywhere):
        
static char too_many_tags_test[sizeof(int)*8 - LENGTH(tags)];

Has anyone better solution?

-Ph

-- 
Premysl "Anydot" Hruby, http://www.redrum.cz/