Merge branch 'dev' into 'master'

Implement first versions of file browser, text viewer and image viewer

See merge request bohacfr2/apo-sem!1

feat: add mzapo sdl

refactor: cleanup build flags

refactor: move gui elements to gui library

fix: use rpath instead of ld library path

refactor: split pheripherals to separate library

refactor: add makefile option for argument in environment

feat: add option to run on x86 computer with sdl

fix: makefile ovewrite of cflags

fix: remove missing variables from Makefile

feat: create initial structure for image-viewer