A criteria is a string in the form of `[class="regex.*" title="str"]`.
It is stored in a struct with a list of *tokens* which is a
attribute/value pair (stored as a `crit_token` struct). Most tokens will
also have a precompiled regex stored that will be used during criteria
matching.
for_window command: When a new view is created its metadata is tested
against all stored criteria, and if a match is found the associated
command list is executed.
Unfortunately some metadata is not available in sway at the moment
(specifically `instance`, `window_role` and `urgent`). Any criteria
string that tries to match an unsupported attribute will fail.
(Note that while the criteria code can be used to parse any criteria
string it is currently only used by the `for_window` command.)
This also fixes a bug where issuing a new "workspace a output b" command
for an already assigned workspace would not work (the old config would
be found first and used instead).
When yes, the old behaviour of adding half the inner gap around each
view is used.
When no, don't add any gap when an edge of the view aligns with the
workspace. The result is inner gap only between views, not against the
workspace edge.
The algorithm is not perfect because it means the extra space is
distributed amongst edge-aligned views only, but it's simple, looks good
and it works.
