Basic R package information
Build infrastructure
Basic pointer testing
Replace Rcpp::as with XPtr for modifiable access
With- and without- copy pointer versions working
Last-gasp changes to odeint and README

This is going to change now that odeint is included in BH
Progress on getting ODEs working
Basic integration working
Controlled stepper interface
Things for testing
Changing mind on class-based approach
Remove the harmonic integrator test case
Remove old files
First version that kind of makes sense.
Basic adaptive integration
Tidy up exports
No longer using odeint except for through BH