* add travis directorie cache for arm sdk
* Travis. Test if make all in one job would work. And how slow/fast.
* Travis. Check that the old method with a couple specific targets still works.
* Rebased master and build all targets again.
* Make verbosity level 0 even less verbose, was still too much for travis in one mega-jumbo-all-target build.
* Even less output from make in verbosity level 0. Some Makefile symbol name cleanup too.
* arm_sdk_install did not check if allready downloaded and installed. Added checks and deps. Travis caching might work better now...
* Build all 56 targets to test Travis caching perf.
* Build all 56 targets to test Travis caching perf. Again. Now with correct yml arrsy syntax.
* Added installation of ccache and also to Travis cache. Caching the cache.
* Travis. Remove some unused APT libs, to see if this affects caching and build times.
* Travis. YAPT (Yet another perf trial). Remove all apt package install.
* Disaster. Put back installation if build-essential.
* Disaster still. Put back installation if zliblg-dev.
* Disaster, again. Put back installation of libc6 .
* Travis. Minimizing APT installation as it not be cached, issue 5876 on travis-ci github.
* Travis. Added comment on target specification.
Anders Höglund
nathan