* add temporary compile test shell script
* Extended support of SKIP_VERSION to make invariant compile results during testing.
* build_keyboard.mk, tmk_core/rules.mk: add LIB_SRC, QUANTUM_LIB_SRC support
Support compiled object enclosed in library.
e.g.
```
LIB_SRC += xxxx.c
xxxx.c --> xxxx.o ---> xxxx.a
```
* remove 'ifdef/ifndef USE_I2C' from quantum/split_common/{i2c|serial}.c
* add SKIP_DEBUG_INFO into tmk_core/rules.mk
When SKIP_DEBUG_INFO=yes is specified, do not use the -g option at compile time.
* tmk_core/rules.mk: Library object need -fno-lto
* add SKIP_DEBUG_INFO=yes
* remove temporary compile test shell script
* add '#define SOFT_SERIAL_PIN D0' to keyboards/lets_split/rev?/config.h
* quantum/split_common/serial.c: Changed not to use USE_I2C.
* Refactor lets split to use split common code
* Refactor lets split to use split common code
* Build fixes for OLED_sample keymap
* Build fixes for OLED_sample keymap - attempt to reduce firmware size
* pull fuse settings for bootloader jump
* fix 32a chips
* make automatic bootloader selection optional
* quantify bootloaders
* fixs #164, speeds up dfu reset
* fix for chips w/o usb
* missing an n
* fix bootloader sizes, use words for addresses
* fix bmini, pearl, and [[ issue, make things quiet
* ignore avr errors on arm for now
* update settings for the light
* document bootloader stuff
* add bootloader title
* Moved duplicated defines out of inappropriate source files (matrix
pins in keymap subdirectory)
* Eliminated default keymap directory
* Hardcoded serial keymap to use serial defines and EE_CONFIG
* Hardcoded i2c keymap to use i2c defines
