1.5: update version to 1.5.1

arch/arm: add sample for nommu bare-metal Cortex-M3 with newlib

arch/arm: add THUMB interworking support

Add config option to build wtarget code with THUMB interworking.
This is used to build the C library as well as all other code
that runs on the target.

arch/arm: add THUMB mode config option

arch/arm: no need to check for the ABI option

The ABI option can not be set if EABI was selected,
so no need to check for it.

arch/arm: add support for noMMU

Some ARM cores do not have an MMU (eg. Cortex-Mx and Cortex-Rx series).
Thus, allow the user to configure out the MMU for ARM.

libc/newlib: allow using CVS snapshots

The newlib "team" rolls new releases about once a year (december).
This is quite a long time between releases, in case code was fixed.
So, allow user to use a CVS snapshot to benefit early from fixes
and enhancements to newlib.

functions: allow using sub-dir of a module

Some projects' module (eg. newlib) are checked-out into a sudirectory
rather than into their own directory. Handle this case in the CT_GetCVS
function.

libc/newlib: allow using newlib with archs other than avr32

libc/newlib: fix namespace in config file

C library config options should be prefixed with 'LIBC_'.