Gardening: typos, formatting, updates

[paulmakepeace]

I worked through the first half and made some minor updates & fixes - HTH. Feel free to use however you like; happy to make edits/separate commits if needed. Thanks for providing this book!

• removed trailing spaces
• fixed some indentation errors
• minor text clarifications
• unnecessary print (AFAIK!)
• fixed typos (V vs Z) & ambiguity in the Memory layout
• update to new numpy array format output
• added globals to make timeit work (not sure a better way)
• half-heartedly added spaces after commas

[rougier]

Many thanks, this is much appreciated!

[rougier]

Need to update the website as well