Upgrading f_cc_megeath[...] with better axes.

This should address Issue #3. But -- one thing I just noticed! My previous color-color diagrams do NOT have the problem of "sources outside the bounds of the cc plot". I may have been using stricter cuts in those cases. BUT! In this case, I am basically using every source that even HAS both a median J-H and H-K color, and the plot turns out pretty good-looking.

I'll have to meditate on this.