icat: renamed feature from icat.feature to icatexplorer.feature
ADMIN: icat rename part 1: u.a.d.s.icat.feature --> u.a.d.s.icatexplorer.feature
ADMIN: icat rename part 2: u.a.d.s.icatexplorer.v42.feature --> u.a.d.s.icatexplorer.v4.feature
ADMIN: icat rename part 3: u.a.d.s.icatexplorer.v42.rcp --> u.a.d.s.icatexplorer.v4.rcp
ADMIN: icat rename part 4: change package names in u.a.d.s.icatexplorer.v4.rcp
ADMIN: icat rename part 5: fix product definition
ADMIN: update/add .gitignore