tools: be much more specific about python versions

This should make sure that there is both a python2 and python3
interpreter on the system (and not just python3).

Fixes my previous commit that used the AM_PATH_PYTHON macro to check for
py2 and py3 which apparently stops at the first python interpreter it
finds, even if it doesn't satisfy the version requirement. Now we only
use that to check for py2 and explicitly look for a python3[.x] binary.
make: warn if old variables

Alert people using make system v3 that the old tinyos variables no
longer do anything and point them to the make system docs.
tools: setup python3 directories successfully
make: Update message if old envvariables are found

The new warning is more direct about what to do to fix the warning.
make docs: Better intro to make system readme

The make system readme now gives a basic primer on how to compile tinyos
applications.
tools: do not compile msp430/cppbsl on mac

This tools explicitly looks for `linux/serial.h` which will not exist on
a mac.
Clarify how the new approach works.
tools: copy jar files into $prefix/lib/java

Only if requested by ./configure --prefix=...
"make uninstall" without errors
Seperate between python2 and python3 to ensure complete removal of files when doing "make uninstall"
Merge pull request #301 from jdede/fix-uninstall

tools: Fix "make uninstall" for CoAP, some python files, and 6lowpan tests.
nesc: bump package version to 1.3.6
BLIP: fix bad merge

I clearly missed this at some point. UDPEcho should compile now.
CoapBlip: fixed RPL compile error.

Need to specify the objective function in RPL now. It used to be an ugly
define buried in the RPL code.
mv Deprecated to deprecated to conform to TEP 3
fixed motelist2: updated the makefile with the new destination directories; Support library renamed for better understanding
tossim: put -I back in PFLAGS for micaz/sim

In the transition to the new make system I somehow forgot to include the
-I in each PFLAGS line in platforms/sim/micaz. This adds them which
should allow tossim to compile.
simplifications: bootstrapping binutils in patch (removes the dependency of autotools), no bootstrapping for gcc, and removed header overwriting in libc (diff showed that both of them is done in the tarball)
fixed datadir, simplified configure parameters (doesn't install to /usr/doc)
cleaned up ucmote include rules