Split getXIntercepts() to be more readable.
Added getYIntercepts()
-Made genPwrArray modular
--Changed current one to genPwrArray.f2
--Added logic to choose between genPwrArray fxn in createPwrFrame()
-Separated the dfGuide function.
-Added test for dfNumerator in genPwrArray()
-Added ability to specify max sample size in createPwrFrame()
-Created infrastructure in plotPower for finding either df or power.
-Changed 'cutoff' to 'power'
Added r2tof2()
Removed ability to scatterplot. It's useless.
Added logic for guides in plotPower()
Changed default max sample size to 1000.
Changed cutoff -> power in getXIntercepts()

Added getYIntercepts()
Added ability to find power from array of dfs.
Added r,r2, and d power generators.
Fixed power generators
-They were not returning the power array, but the power.htest object.

-Added default alternative value ("two.sided") to createPwrFrame
Added ability to plot both df and power guides, because why not?
Added attr('test') to pwrFrame. Lets one know which test/effect-size the pwrFrame is built on.
r2tof2 now actually returns f2
Added 'r' to the createPwrFrame stop()
Added better support for cohen's d
- Added ability to specify sample type
Added example plots.
-Added database of cohen's effect sizes.
-Added ability to consider the standard effect sizes in addition to specified es's.
Changed default dfs to 4:1000

Fixed cohen option.
Updated todo list. Removed completed.
Added GPL2