ocaml / opam

This bug-fix release fixes some small issues 1.2.1 had, and brings a couple improvements:

Fixes:

• The state-cache was broken on OSX, which could cause longer startup times
• opam config report didn't report the external solver correctly
• --dry-run --verbose didn't give the expected output
• Providing a simple path to an aspcud executable as external solver without expliciting the arguments works again
• Fixed a fd leak on solver calls
• opam list now returns 0 when no packages match but no pattern was supplied

Improvements:

• Conflict messages now report the original version constraints without translation, they are more concise in some cases
• Some new opam lint checks, opam lint now numbers its warnings and may provide script-friendly output
• Feature to automatically install plugins, e.g. opam depext will prompt to install depext if available and not already installed
• Priority to newer versions even when the latest can't be installed (with a recent solver only. Before, all non-latest versions were equivalent to the solver)
• Added opam list --resolve to list a consistent installation scenario
• Be cool by default on errors in opam files, for easier format updates without shouting at end-users

As usual, see the more detailed changelog for details.