add a new data type "version"
version is a concept that is often used in our domain, it should be a first class concept in ABS (instead of using only enum, boolean, int or string)
It should use a semantic using 4 digit as in semantic versionning:
major.minor.patch.metadata
Each of them will be used to help to compare them (cf. #172 (closed))
Edited by Vojtisek Didier