coverted tutorial to ipynb
reconstituted markdown version of shell tutorial
updated variables.ipynb
Converted tutorial to ipynb
updated data structures notebook
updated flow control notebook
Merge scopatz 'flow-cont' PR 21
Merge scopatz 'vars-types' PR 18
Merge scopatz 'data-struct' PR 20
Merge scopatz 'strings-io' PR 19
added explanation about comparisons, genotype example details
renamed variables, avoiding camelcase
added inline exercise with tests, light-handed change of variable names
Removed math.log example and replaced half-baked examples with more concrete elementary ones.
Expanded examples and converted notebook to v3.
Changed position of jocular string comparison
Corrected variable mispelling and missing file name
Added blank cell, explained for..else, changed battlestar to python
Moved block of comparison operator before if syntax
Minor text and link fixes