- simplify the makefile
- changing behavior depending on lessc being installed is
surprising and makes the Makefile less readable
- failing with `make: lessc: No such file or directory` is helpful,
but `make: No rule to make target 'src/css/riot.css'` is not
clearly indicating that `lessc` was not found
- don't rebuild `riot.css` when generating HTML output
- anyone touching the less file will have to manually call
`make src/css/riot.css -C doc/doxygen`
- this happens so rarely that implementing a convenient mechanism
is not worth the trouble
Fixes https://github.com/RIOT-OS/RIOT/issues/8122
lessc (node-less) and lesscpy do not produce the same output.
There are some minor whitespace +-1 in color values which
are not important but the output file is not stable
However lesscpy removes comments and so the license of the output file
As it produces an invalid file it support is dropped.
https://lesscpy.readthedocs.io/en/latest/#differences-from-less-js
fixes tons of false warnings on cpu_conf.h headers in cpu
/tmp/RIOT/cpu/atmega1281/include/cpu_conf.h:12: warning: the name `/tmp/RIOT/cpu/atmega1281/include/cpu_conf.h' supplied as the second argument in the \file statement matches the following input files:
/tmp/RIOT/cpu/atmega1281/include/cpu_conf.h
Please use a more specific name by including a (larger) part of the path!
