Add more to .gitignore
Add a Makefile
Add some low-level code
Add simple Composition constructor for OCPs
Change some classes to structs
Separate GslFunction helper into own files
Update GslBrent for previous commit
Add simple struct to represent functions
Add first attempt at radial quadrature code
Remove single-exec assumption from Makefile

Pave the way for this project having more than one executable
Add RadialIntegral test