Bump YARP_VERSION_TWEAK

IDL generated files are now using YARP_UNUSED and are not compatible
with previous versions. [Thanks @francesco-romano]
[thrift] add editor tests, fix multi-set messages
[thrift] make sure testing is done against test name server
[thrift] add missing return values
dial back the crazy a little on testing swig versions
check-bindings.sh: Allow to change the tested swig versions using the SWIG_VERSIONS env var
.travis.yml: Download latest swigs.zip version
.travis.yml: Test only a limited number of swig versions
[YARP_OS/Log] Fix deprecated warnings in old Logger
Restore "warn_suppress" variables and mark them as YARP_UNUSED

This should suppress all relative -Wunused and -Wunused-result warnings
with all the different compilers
Cleanup
Fix -Wunused-but-set-variable warning
Fix -Wunused-but-set-variable warning
Fix -Wunused-variable warning
Fix a few warnings
Fix a few -Wunused warnings
Cleanup
[yarpview-gtk] Add --keep-above argument
[yarpview-qt] Add --keep-above argument
Add YARP_INT32_FMT and YARP_INT64_FMT defines

These should be used when printing YARP_INT32 and YARP_INT64 variables
instead of %d, %ld, %lld to avoid warnings, for example:

   YARP_INT32 x = 32;
   YARP_INT64 y = 64;
   printf("x = %"YARP_INT32_FMT", y = %"YARP_INT64_FMT, x, y);