allow in-source testing (fixes #23)
Merge pull request #24 from ottxor/testing

allow in-source testing (fixes #23)
resolves #22 and improves cmake argument handling
cmake: fixed install location for share data

* samples, apidoc and misc go now to into PREFIX/share/icnc
* don't mark bat files executable on non-Windows installs
cmake: install libs with SOVERSION