Tracking: libtock-rs driver support

[lschuermann]

Through the libtock-rs breakout session at TockWorld 6 and the subsequent discussion, we concluded that it could be good if (at least) every core-team member would port a given userspace driver to libtock-rs. This issue is supposed to be a tracking issue where developers can sign up for a driver to be ported.

Please feel free to add yourself to this list, and to update it to reflect the current porting efforts:

• adc
• aes
• alarm
• ambient_light
• analog_comparator
• app_state (might not be applicable to libtock-rs)
• ble
• button
• buzzer
• console
• crc
• dac
• gpio_async
• gpio
• hmac (@lschuermann)
• humidity(@hudson-ayers)
• i2c_master
• i2c_master_slave
• ieee802154
• ipc (might not be applicable to libtock-rs)
• kv_system Add key-value support #488
• l3gd20
• led
• lora_phy
• lps25hb
• lsm303dlhc
• ltc294x
• max17205
• ninedof
• nrf51_serialization (probably not applicable to libtock-rs)
• pca9544a
• proximity
• read_only_state
• rng
• screen
• sdcard
• sha
• sound_pressure
• spi
• spi_peripheral
• temperature
• text_screen
• touch
• tsl2561
• udp
• usb

It seems that libtock-rs supports the following drivers that libtock-c does not:

• air_quality
• low_level_debug (could be useful in libtock-c's crt0)