Initial files for homework 1
initial test of creating and passing Integrator structure
Expanded Integrator typedef to include fields, to avoid incomplete type eror
Added function pointer
Apparently functional implementation of explicit Euler method
Cleanup and bugfixes on explicit Euler method
Apparently working implementation of rk4 method
Added second-order Adams-Bashford method
Added command line input of timestep and numsteps, with error handling
cleanup and bugfixes
Added makefile and changed dependencies
Removed .DS_Store