updated release script to use adms from git
bump to 0.0.19, add use of VERSION files

* unify the versioning with VERSION file
* see:
  http://svn.r-project.org/R/trunk/configure.ac
  http://stackoverflow.com/questions/8559456/read-a-version-number-from-a-file-in-configure-ac
add VERSION files

* one in each directory
build: look for Git short hash

* based on the .git directory, decide if it is a clone
qucs: use Git hash on About and `qucs -v`
core: search for Git hash
core: add Git hash to `qucsator -v`
cmake: use VERSION file and add Git last hash
cmake: add VERSION and Git support to qucsator
add git tag to qucsconv
update main NEWS.md

* let us try to keep track of the changes in a single place.