Remove assembly forcing stack.

Fixes #51

There should be no reason for manually trying to load the stack.  Cortex
devices can be programmed with only C, and any code that needed this
would indicate broken vectors.
[examples f1] ADC+DAC very basic example

Just shows some basic working examples of using the DAC with the ADC. No
special features, but very little hardware required to demonstrate.
[l1] fix whitespace and missing license info

Earlier additions to the L1 support were not correctly using linux
coding guidelines as specified in /HACKING.

Some examples were also missing license information.
[l1] PWR: fix style for common code

Code added for L1 to support the PWR Control block didn't properly
follow the HACKING_COMMON_DOC guidelines.  The naming was wrong, and
some headers were missing.  This commit has no functional changes, it
only addresses the style and structure problems.
[l1] Update to newest ref man definitions

Support for the Medium+ and High density parts, mostly by way of extra
irqs and register definitions.
[l1] rcc: support MSI clocking

Some new definitions and helpers.  Main change really that the list of
preconfigured clock configs is no longer restricted to HSI/PLL
[stm32] Support the "new" BCD style RTC peripheral

Add the register definitions and some of the most basic helper functions
for the new style BCD RTC module found on the F2, F4, L1, F3 and F0.

This tries to keep as close to HACKING_COMMON_DOC as possible, while
maintaining sane names.
Add examples making use of the RTC

Add an example using the RTC to help with a lower power design.  This is
a sister example to the existing "button-irq-printf", which is
functionally identical, but uses far less power.

There's more tricks that can be done to lower the power even further,
but this shows a few of the early steps that can be done, using the RTC
wakeup instead of a timer.
[flash] l1: use "proper" bit definition naming.

Part 1 of 4: updated l1 to use flash_<reg>_bit instead of just flash_bit
[flash] f1: use "proper" bit definition naming.

Part 2 of 4: updated f1 to use flash_<reg>_bit instead of just
flash_bit
[flash] f2: use "proper" bit definition naming.

Part 3 of 4: updated f2 to use flash_<reg>_bit instead of just
flash_bit
[flash] f4: use "proper" bit definition naming.

Part 4 of 4: updated f4 to use flash_<reg>_bit instead of just
flash_bit
Add notes on build prerequisites
[stm32-dma] Eliminate redundant write.

Clearing a single bit in DMA_CCR, then immediately writing a 0 over the
entire register is completely redundant on the F1, F3 and L1 DMA
peripherals.  (Unlike the F2 & F4 DMA Peripheral, where this is
required)
[stm32] Use common memorymap include for consistency

Most peripheral headers simply include <libopencm3/stm32/memorymap.h>
which, like the rest of libopencm3 requires the correct compiler define
flag to be set.  A few peripherals were directly including the platform
include, libopencm3/stm32/xx/memorymap.h, and in some of those cases it
wasn't even correctly including the correct platform.  (Likely the
result of copy/paste errors)

These direct includes have been eliminated
Merging pull request #78 "Remove assembly forcing stack."

Merge remote-tracking branch 'karlp/destroy-all-the-asm'
Merge pull request #79 "More L1 support (and f2/f4 rtc)"

Merge remote-tracking branch 'karlp/pr_more_l1_rtc'
Merge pull request #81 "[examples f1] ADC+DAC very basic example"

Merge remote-tracking branch 'karlp/pr_f1_adc_dac'
Merge pull request #84 "Pr flash reg rename"

Merge remote-tracking branch 'karlp/pr_flash-reg-rename'

Conflicts:
	include/libopencm3/stm32/l1/flash.h
Merge pull request #85 "Add notes on build prerequisites"

Merge remote-tracking branch 'karlp/pr_prereq_docs'