fixed bug if data_index < 1 in lightcurve
Fixed some limit errors in cross-correlation
Merge branch 'master' of https://github.com/justincely/astroraf
added __str__ method to lightcurve
Added ability to extract over wavelength ranges
Merge branch 'master' of https://github.com/justincely/astroraf
updated license information
re-organized functions.  Trying to break up __init__ into more function cals, less procedure