Makefile.include: revised verbosity control

This should be more friendly to legacy operating systems that
don't support multiple shell commands per line. Note that
architecture-specific overrides need to be adapted, if verbosity
control is desired for them as well.
Minor code style fix
Merge pull request #310 from oliverschmidt/master

Minor code style fix
Merge pull request #309 from frtos-wpan/verbosity-v2

Makefile.include: revised verbosity control
Be consistent with tab chars in Makefiles - yet again...
Merge pull request #311 from oliverschmidt/master

Be consistent with tab chars in Makefiles - yet again...
Be consistent with tab chars in Makefiles.
Merge pull request #312 from oliverschmidt/master

Be consistent with tab chars in Makefiles.
unistd.h doesn't seem to be necessary but breaks the MS VC build.
Merge pull request #313 from oliverschmidt/master

unistd.h doesn't seem to be necessary but breaks the MS VC build.
Recent changes in telnetd make exporting of those two necessary.
Merge pull request #314 from oliverschmidt/master

Recent changes in telnetd make exporting of those two necessary.
Support the recently added verbosity control.
Merge pull request #315 from oliverschmidt/master

Support the recently added verbosity control.
Suppress some usual warnings.
Merge pull request #316 from oliverschmidt/master

Suppress some usual warnings.
Several minor consistency improvements.
Merge pull request #317 from oliverschmidt/master

Several minor consistency improvements.
Merge remote-tracking branch 'upstream/master'