keep opam's bin/ at the same place in the PATH list during a switch
Merge pull request #1189 from vprevosto/master

keep opam's bin/ at the same place in the PATH list during a switch
Changed default preferences to avoid downgrades when possible.
Added help entry for OPAMCRITERIA with default value printed out.
Reorganised dose patches to match the ones now present in dose 3.1.2 opam package
Experimenting a different default value for the external solver preferences
Merge branch 'master' of github.com:rdicosmo/opam

Conflicts:
	src/core/opamGlobals.ml