* style: remove extra space
* feat: handle xrm_Char in config parser
Handle the `xrm_Char` case in the (rasi theme) config file parser. This
should properly handle configuration like
```
matching-negate-char: "\0";
```
and
```
matching-negate-char: "-";
```
* refactor: don't handle mem in xrm_Char case
`mem` shouldn't ever be set when `XrmOption` is `type` `xrm_Char`.
Therefore, there is no need to check it and free it. Remove that logic.
* refactor: further condense logic
* style: s/Everythin/Everything/
* style: s/parsing an section/parsing a section/
...and missing period.
* feat(lexer): add CHAR token
Add a `CHAR` token that takes things of the form `'<char>'` or some
specific backslash escape sequences like `'\''` and `'\0'`. For now,
save it as a `T_STRING`.
* refactor: define char property type
* feat(parser): add cval and T_CHAR
* refactor: use char property for xrm_Char
Instead of using strings for property elements of type char, use
characters, which were recently added to the grammar.
