first attempt at porting libopencm3 to energymicro

unless sources are explicitly given, the linker scripts and make files
were copied over from the stm32/f1 port.
made blinking a led on efm32 possible

this includes all register definitions for the gpu and mcu modules, but
not all their bit definitions
overhauled documentation

includes minor refactoring in example code and modification of how the
generic and the tinygecko specific vector.h go together (bringing it in
line with stm32/f1's memorymap.h)
make doxygen ignore .d files

.d files are created to track Makefile dependencies and don't contain
real code
efm32: created memory map from all base addresses
efm32 tinygecko: defined interrupts

there seems not to be anything family specific about the interrupt
vectors of m3 based efm32 systems, thus renaming vector.h to irq.h
efm32: minor documentation enhancements
efm32: make all interrupts usable in vector table

* define weak symbol for ${irq_name}_isr
* put them in the rom vector table
* declare reset_vector weak in case someone wants to insert code there
* remove null_handler (null handlers should be only requested
  explicitly, and finding out why the chip gets stuck is easier than
  determining whether or not a no-op interrupt handler was executed)
make doxygen ignore __attribute__

doxygen doesn't understand __attribute__ and constructs bogus call
graphs and dependencies from it.

according to the doxygen maintainer[1], this is the way to deal with it.

[1] http://sourceforge.net/mailarchive/message.php?msg_id=20085215
efm32 example: enhanced makefiles
added upload target for segger's JLink tool

this is quite a hack, but the only way i know of by which firmware can
be uploaded to the efm32tg-stk until OpenOCD supports SWD on jlink
fixed a bug in efm32 miniblink example

actually, it wasn't a bug; the compiler just optimized a statement away
until it was declared volatile. inserting a no-op assembler instruction
to make it more obvious what's going on
efm32 tinygecko gpio: implemented all the bit values

along with the actual implementation comes a first attempt to better
structure the doxygen groups. putting all the groups in a bigger one
makes it easier to reference them from the file itself, and makes the
structure clearer on the module page.
convenience functions for efm32 gpio

also, the whole gpio header file is now a big doxygen group, structuring
the convenience functions and the register/value definitions
added efm32 lightswitch example
(efm32: remove todo that couldn't work out)
efm32: energy management unit headers and example
Merge branch 'master' into efm32
follow the license change to lgpl3 in efm32

this follows the license change of the master branches in [43561de]. all
files whose copyright is not my own are originally based on files whose
license has been changed in master.

the expression used for the conversion was:

sed -i -e 's/This program is free software: you can redistribute/This library is free software: you can redistribute/g' -e 's/under the terms of the GNU General Public License as published/under the terms of the GNU Lesser General Public License as published/' -e 's/This program is distributed in the hope that/This library is distributed in the hope that/g' -e 's/You should have received a copy of the GNU General/You should have received a copy of the GNU Lesser General/' -e 's/along with this program.  If not/along with this library. If not/' -e 's/GNU General Public License for more details/GNU Lesser General Public License for more details/' */**/efm32/**/*(.)

[43561de] 43561de3297b88d68753cb4625d6dc48bfb43d71
add missed license headers to efm32 files

some files had nonstandard shared copyright lines, fixed them too