bump version to v1.4.1dev
enhance list toolchains unit tests, also check how many times a toolchain is listed
only consider *unique* subclasses of Toolchain
Merge pull request #628 from boegel/fix_list_toolchains

fix 'eb --list-toolchains'
Merge branch 'v1.4.x' into develop

Conflicts:
	easybuild/tools/version.py