First try at ASR under GeoSSE
First version of GSL ode integrators.

Working for along-branch BiSSE calculations.
Set GSL error handling to pass back to R, not quit.
First version of C++ time machine

No splines, no Q matrices
Models with Q matrices now work (constant rates at least)
TimeMachine works with time-varible Q matrices now
TimeMachine basic spline interface now working.
Attempt at getting time-varying ODEs
Basic testing of time varying GslOde-based models (via GslOdeTime)
Remove old comment.
R-based derivatives.
Convert an R-based derivative into a time-varying version.
Shift test cases to make another new version, without reference to old backends.
Simplified ODE interface, and set up new test cases.
Further simplified ODE generation interface and test cases.
Basic bisse tests pass again
Clear out old tests
Basic MuSSE models working.

Time varying not tested, split models *not* working.
Removed old time machine code and moved new code into place.

Note: at this point, basically all time-dependent models are tragically
broken.
TimeMachine caches input parameters and won't reapply same set again.

As a result, it is cheap to call tm$set().  This is important for the models where TimeMachine exists on both the R and C side, as the C version is a copy (and does not share parameters).  This caused a bug in the initial conditions setting.