add implementation of rtAssertMessage

fixes #56
add staging branch to travis builds

[ci skip]
reduce optimisations in library builds

This fixes the crashing in issue #56.
add -Wcheck to test program compilation
add tests from aldor.org bugreports
add .gitignore files to test dirs
remove more files on make clean
correct CLEANFILES append
use per-library sublib-depend names

When building libax0 after axllib, make will otherwise think the sublib
already exists, because it's there in axllib.
disable pack1 and pack2 tests
fname.c: Add a couple of missing functions
Rename aldormain.c to xyz-aldormain.c; this will allow easier parallel
builds
Rename xyzmain.c to xyz-aldormain.c in .gitignore files
tst_mint.c: No need to import from already cascaded import (Assert will
always import GeneralAssert along with itself).
foamlib tests: Add the option to compile to executable.