Signed-off-by: drkhsh <me@drkhsh.at>

Fixes coding style. Formatting commits suck, incoherent coding style
sucks more.
https://suckless.org/coding_style/

Except stated otherwise in comment.

Fixes coding style. Formatting commits suck, incoherent coding style
sucks more.
https://suckless.org/coding_style/

function prototype with unspecified argument is obsolete since c99.

additionally some of these function which don't take any argument were
being called with a `const char *` arg, which is UB.

fix both these issues by declararing ALL the components to accept a
`const char *`, and name the arg "unused" if it's meant to be ignored.

this gives the compiler a chance to check weather the prototype and
definiton matches or not, which would catch issues like 3c47701.

 - Get rid of camel-casing
 - Don't use all-caps for variable names
 - use LEN()-macro
 - use strncmp() rather than strstr() for prefix-checking
 - clean up the tokenizer-loop and don't use copies
 - make the loop more readable by separating different breaking
   conditions
 - stricter error-checking and cleanup
 - store the layout directly with bprintf rather than having
   a separate buffer

Adding a new keymap component that will
indicate the current keyboard layout (language)
and variant if any was set. I use the
standard X11 XKB APIs to retrieve and parse
the xkb_symbols set with setxkbmap.