stm32:l0: Add RCC register definitions

Tested with a miniblink example on the l053 discovery board.

Only register definitions at this stage, no helpers.
Register definitions from RM0367r2, hopefully the biggest
superset of L0 parts.

Signed-off-by: Karl Palsson <karlp@tweak.net.au>
stm32:l0: Add linker script / memory sizes

Easier to pick a corresponding part.
stm32:l0: RCC: add osc_on/osc_off helpers

These are the routines that have custom switch cases, and aren't easy targets
for pulling out.
stm32/f0: rcc.c Use common version instead of duplicate code.

Pulls out duplicate calls from f0/rcc.c and uses the common version which
also means that f0 can use rcc_peripheral_enable() now which is in common
but not the old rcc versions.
.gitignore correct netbeans project directories
stm32/desig: include in f4 library

The code is all there and working but simply isn't being built.
First cut at an HSI configuration API for rcc on the STMF4 series.

Fixed constant usage, and a AHB frequency computation.

And including an F0 rework of RCC a bit to put the rcc_set_hsi_clock code in
the F0 tree as well, tested on the Nucleo F030RE.

Further generalizing the clock setup to work for HSE and HSI clocks

Conflicts:
	include/libopencm3/stm32/f0/rcc.h