Add support for merge rate parameters per-channel

The only user visible aspect of this change is that QvModelParams now
has two constructors:

    - a 12-argument constructor for the lumped merge rates model;
    - an 18-argument constructor for the by-channel merge rates model

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119841]
Bump version -> 0.5.1

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119842]
Add 'test' and 'check' makefile target aliases

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119843]
Clean up ConsensusCore setup.py to allow MJ to query version cleanly

(via python setup.py --version)

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119856]
Refactor setup.py, fixing current build failure

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119879]
Python libs no longer used

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119880]
Add LICENSES file, which somehow I never had in here

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119881]
Fix license

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119886]
Fix optimization level

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119887]
Add back packages specifier

It is needed for the ConsensusCore native lib to be installed for
Python

[Tracking bug 21562]

[git-p4: depot-paths = "//depot/software/common/ConsensusCore/": change = 119890]