Structure of Python cheatsheet

[jstac]

The content needs to be expanded and the structure could be improved. For example, if/else comes under the heading Functions.

I suggest we start with a headings like these:

Operators (covers *, +, **, etc.)
Data Types
Builtin Functions
Imports
Input and Output
Iterating
Comparisons and Logical Operators
User Defined Functions

Then we can move on to NumPy and plotting.

[vgregory757]

These categories are much better! I started off by rearranging what we have now: 32369c2

[jstac]

@vgregory757 Great, thanks!