initial commit
fix DESCRIPTION
Make a valid package

Add rudiments of documentation and make to use modern package
structure.
add logistic growth curve
typo in equation
add Lotka-Volterra competition model
Add lines.lotkacomp

lines.lotkacomp() draws population trajectories to a lotkacomp plot.
It uses Hank Stevens's primer package to find the trajectories via
numerical integration, and ecostudy now depends on primer.
use legal keywords in logrow.Rd
add lotkaplot
add generic traj method to extract results
tweak plot.lotka
implement and use traj.lotkacomp()
edit docs
version to 0.4
make ricker() a canonical R function

Function rickerplot() was split to separate functions doing the
calculations (ricker) and plot the results so that it works
like a normal R function.
Change logrow into standard R function ranlogist

Function logrow was renamed to ranlogist, and split into simulation
function that returns the results and to plot and lines functions.
traj.lotkacomp 'time' can be parametrized plus fixes

The start 'time' is now 0 (instead of 1) and the length of trajectory
time can be parametrized, and finer or longer 'step' over time is
allowed -- all as user arguments.
lotkacomp traj() preserves the classes ode() gives
add lines.traj and make plot.traj 'type' configurable
typo in commit 57ff85d