New scroll snap methods and hooks to full customization

[koron]

See alsor #559 and #555

• Three scroll snap mode, be switched manually

  • New three keycodes
    • SSNP_VRT vertical scroll snap mode (default)
    • SSNP_HOR horizontal scroll snap mode
    • SSNP_FRE free scroll mode
  • Can be persisted to EEPROM with KBC_SAVE
  • Current mode is displayed on OLED; VT, HO, SCR

• Can revert to previous behavior up to 1.3.2

  • Add #define KEYBALL_SCROLLSNAP_ENABLE 1 to your config.h

• New overridable functions

  • How trackball movement is applied to mouse movement
  • How trackball movement is applied to mouse scroll

• Removed a set of keycodes for directly changing RGBLIGHT modes from Keyball39 and 46 keymaps

  This is to register the SSNP_* keycodes.
  Please use RGB_MOD and RGB_RMOD instead of those.

TODO:

• documents
• comments
• indicate current scroll snap mode
• add keycodes to keymap
• more documents

[koron]

Differences in firmware size due to this change

name	before	after	diff	oversized
keyball_keyball39_test.hex	22,730	22,730	+0
keyball_keyball39_default.hex	27,396	27,382	-14
keyball_keyball39_via.hex	27,158	27,138	-20
keyball_keyball44_test.hex	22,724	22,724	+0
keyball_keyball44_default.hex	27,390	27,376	-14
keyball_keyball44_via.hex	27,152	27,132	-20
keyball_keyball46_test.hex	22,686	22,686	+0
keyball_keyball46_default.hex	27,352	27,338	-14
keyball_keyball46_via.hex	27,086	27,066	-20
keyball_keyball46_test_Left.hex	22,686	22,686	+0
keyball_keyball46_test_Both.hex	22,686	22,686	+0
keyball_keyball46_via_Left.hex	27,086	27,066	-20
keyball_keyball46_via_Both.hex	27,086	27,066	-20
keyball_keyball61_test.hex	22,850	22,850	+0
keyball_keyball61_default.hex	27,716	27,702	-14
keyball_keyball61_via.hex	27,476	27,468	-8
keyball_one47_test.hex	18,958	18,954	-4
keyball_one47_default.hex	21,758	21,754	-4
keyball_one47_via.hex	24,548	24,544	-4

avg(diff)
-9.26316