implement arduino style ruuvi.millis() to access systick counter
Fixed comment, this works (at least for now)

We'll have to see if there is integer overflow before 2^32-1
Use lua_pushnumber to avoid overflow issues coming from being cast to signed type
merge fixes from experimental branch
Merge branch 'master' into revc1gsm
merge fixes from experiments
Merge branch 'millis' into revc1gsm

We require this helper for timeouts
enable the card by default
merge the baudrate workaround
Add missing HSE_VALUE configuration for RuuviC1. Without this, serial port clocks are off.
Update CMSIS Cortex-M4 Device Peripheral Access Layer System Source File to version 1.1.0 with a 48MHz system clock.
merge thautas serial clocks fix and revert my hacky workaround
Merge pull request #26 from rambo/revc1sdcard

Revc1sdcard (errata)
Merge pull request #24 from rambo/millis

implement arduino style ruuvi.millis() to access systick counter
Merge pull request #27 from rambo/revc1gsm

Revc1gsm
Merge pull request #28 from rambo/revc1i2c

Revc1i2c
Merge pull request #29 from thauta/master

Fix RuuviC1 HSE initialization and update the clock configuration file created with Excel.