refactor: use libmagic even for ppm

feat: add file browser base

refactor: use libmagic instead of custom handling magic numbers

refactor: add gitignore to docs

docs: move doc to user manual

docs: add date

docs: make appropriate code modifiers

refactor: cleanup build flags

fix: includes for jpeg

docs: add manual and and compilation documentation

docs: correct formatting

docs: add code documentation

fix: showing unscrollable files correctly

fix: opening empty file

refactor: move gui elements to gui library

feat: use ledstrip to show vertical scroll

feat: use ledstrip to show file loading bar

feat: put errors to enum instead of magic constants in code

feat: use pheripherals in text viewer

refactor: use name and line pointer instead of local variable