Merge branch 'release/0.4.0'
A few bug fixes. Some checking about existence of input files.
Merge branch 'release/0.4.2'
Merge remote-tracking branch 'origin/master'
Merge branch 'release/0.4.2'

Conflicts:
	chemex/__init__.py
Merge branch 'release/0.4.2'
Commit of 0.4.2
Merge branch 'master' into develop