Change 'indicator' to 'led' everywhere possible

Change 'indicator' to 'led' everywhere possible

The code currently uses the two names interchangeably.
Settle on 'led', because it is shorter, more recognizable, and what we
use in our API (though of course the parser still uses 'indicator').

In camel case we make it 'Led'.
We change 'xkb_indicator_map' to just 'xkb_led' and the variables of
this type are 'led'. This mimics 'xkb_key' and 'key'.
IndicatorNameInfo and LEDInfo are changed to 'LedNameInfo' and
'LedInfo', and the variables are 'ledi' (like 'keyi' etc.). This is
instead of 'ii' and 'im'.

This might make a few places a bit confusing, but less than before I
think. It's also shorter.

Signed-off-by: Ran Benita <ran234@gmail.com>