Fixes: https://github.com/libopencm3/libopencm3/issues/1033

This removes the dependency on awk and should fix #732
python was already a dependency, for the irq generation

Show off how modern we are, building everything!

Fixes https://github.com/libopencm3/libopencm3/issues/870

Copy edited.

Not just m3, and add some newer parts while we're here.

Interim fix.  See https://github.com/libopencm3/libopencm3/issues/732
and https://github.com/libopencm3/libopencm3/pull/731

This has hurt many many many people over it's lifetime, by confusing their
multilib toolchains.  Simply drop it outright.  People who _really_ know what
they're doing are still perfectly entitled to "install" portions of this
project in suitable locations for their own use.

Boo ST.

Most changes are noise from doxygen.
Readme udpated to explain newer FP_FLAGS for m7
stm32f7 library is skipped if the toolchain doesn't support it yet.

Renamed every instance of variable CFLAGS in target specific Makefiles
to TGT_CFLAGS to free up CFLAGS for user defined compiler flags.

Added information in README.md about existence and usage of CFLAGS
environment variable in build process.

Including removing the extremely unhelpful DETECT_TOOLCHAIN option.

This converts all the YAML files to JSON files, as json parsing is built
into python instead of being a separate library requiring installation.

YAML is a superset of JSON, but putting comments in is not quite as obvious
as it is in yaml.

The following glue was used to convert yaml to json:
python -c 'import sys, yaml, json; json.dump(yaml.load(sys.stdin), sys.stdout, indent=4)' < $1 > $2

Clearly I haven't tested this on every single platform, and this
doesn't address the large blobs of yaml in the lpc4300 scripts directory,
only the cortex NVIC generation process.

I've tested a few IRQ driven example apps, and I've checked the generated
output of some known cases like the LM3s that has explicit gaps, and they are
all generated correctly.

We currently default to "-mfloat-abi=hard -mfpu=fpv4-sp-d16" for M4F cores, and
and variations of "-mfloat-abi=soft" for the others. Keep the M4F default, and
move others to no FP flags for consistency, but allow overriding these flags
via the FP_FLAGS environment variable.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

Where the library is installed has quite an affect on what -L and -I
flags are used.  If you install into the toolchain, you don't want
to use them at all, but if you install out of tree (/opt/mycm3 for
example) you need to specify the -L and -I flags.

Update the documentation and the example makefiles to support this

Agreed to by all the significant contributors to the library.