test: Streamline test suite a little

This change aims to streamline the integrationtest suite and reduce friction when running (parts of) test suites.

Changes:
- add `test-testname` to makefile to easily run one suite
- made skipping tests first class citizen in test.sh (all available testsuites and the reasons they are skipped are now better exposed and discovered)
- suppress some output of gotest unless there is an error
- no longer build binary for examples and gotest suites
- removed .SILENT from makefile as it being applied to only some targets makes it feel weird (I just learned about this option btw, feel free to comment on this change)
- move individual tests out of `test.sh` and into `test-misc.sh`
- introduced the concept of testsuites to `test.sh`

test/test-headerfmt.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 # check that headers are properly formatted
 
-echo running test-headerfmt.sh
+echo running "$0"
 
 #ROOT="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && cd .. && pwd )"	# dir!
 ROOT=$(dirname "${BASH_SOURCE}")/..