Mostly typos, grammar and formatting

[robertdapice]

Mostly tiny typoes, but two more meaningful changes:

• The 'introduction' section to the Deque chapter has gone awol. I think it was due to duplicative field declarations at the top of the .md file. I've fixed these, but you'll need to rebuild to see if it's working now?
• This is super pedantic and trivial: but I changed the ‘num = 7’ used in your Hot Potato example to 9. When it was ‘7’, I assumed it reflecting the Josephus story (i.e. ‘killing’ every 7th person). Actually your implementation kills every 8th person (or every (n+1)th person). I thought about changing the implementation to actually killing every nth person, but then it was inconsistent with your description of the hot potato algorithm immediately above. I thought it easier to change the number from 7 to remove any potential confusion with the Josephus story.

A few things I didn't change, but might need some attention:

• Markdown rendering is broken in a few places. Doesn't seem to be invalid markdown; could there be a bug in the markdown -> HTML library you're using? See example of putting Hexadecimals in number coding:
  
• The Binary Heap section is described as being implemented with the ‘list’ data structure. Should this be renamed to an ‘array’ data structure, given you’ve already addressed lists as an abstract data type (that itself is not, in fact, implemented with an array)?

[ozan]

@robertdapice awesome, massive thanks for these. I'm embarrassed that you found so many typos :( . I'll move the issues you found to new tickets and merge this.