src: Name wceeprom module preferences module

This renames the wceeprom module and is the first step to decouple the
preferences and their storage in the backend within the EEPROM.
src: preferences: Rename WcEepromData to prefs_t
src: preferences: Rename wcEeprom_init() to preferences_init()
src: preferences: Rename wcEeprom_getData() to preferences_get()
src: preferences: Rename wcEeprom_writeback() to preferences_save()
src: preferences.h: Fix coding style guidline violations
src: preferences.c: preferences_save(): Add todo items
src: preferences.c: Make internal variables static
src: preferences: prefs_t: Rename UserEepromParams to user_prefs_t
src: preferences: Rename DisplayEepromParams to display_prefs_t
src: preferences: Rename PwmEepromParams to pwm_prefs_t
src: preferences: prefs_t: Rename userParams to user_prefs
src: preferences: prefs_t: Rename displayParams to display_prefs
src: preferences: prefs_t: Rename pwmParams to pwm_prefs
Merge branch 'master' into feat/preferences

Conflicts:
	src/preferences.c
	src/uart_protocol.c
src: wceeprom.h: prefs_t: Rename swVersion to version
src: preferences: prefs_t: Rename structSize to prefs_size
src: preferences: Change signature of preferences_save()

This changes the signature of preferences_save() and makes it easier to use as
the start and length parameter are no longer required. As reading values from
the EEPROM and comparing them to the copy hold in SRAM is a cheap operation,
this is not too big of a performance hit. Furthermore the function is called
only seldom and it makes it easier for the callee if he does not need to keep
track of what was actually changed.
src: preferences.c: wcEeprom_writeIfChanged(): Refine Doxygen comment block
src: preferences.c: Remove unused headers