Outsource global variables, Optimize comments

- outsource global variables and objects
    - move from config.hpp to global.cpp / hpp
    - rename config.hpp, thus change all includes
- re-arrange includes -> in source files instead of header

- optimize / make function comment titles more consistent
- optimize comments overall

- add several temporary files to gitignore
- fix unused variable compiler warnings

.gitignore

@@ -1,15 +1,29 @@
 # ESP-IDF default build directory
 build
+sdkconfig.old
+dependencies.lock
 
 # VIM files
 *.swp
 *.swo
+**/.cache
+
+# VS-code
+settings.json
 
 # drawio files
 *.bkp
 
 # freecad backup files
 *.FCStd1
+*.FCBak
+# stl files are usually temporary
+*.stl
 
 # kicad backup files
 pcb/*/*backups/
+
+# other
+octave-workspace
+del
+screenshots