minor fixes to section 2
add note about functions behaving like values
add note about function inputs being referred to as arguments or parameters
Added .gitignore
fix some minor issues in sections 3,4 and 6
Added proposed edits to Chapter 3.
Added proposed edits for Chapter 4.
fix minor mistake in section 3
change some boring examples in section 4
merge master and fix conflict
add section 3 edits, and fix merge conflicts
Merge pull request #5 from eplawless/Edit-Chapter4

Added proposed edits to Chapter 4.
Merge branch 'master' into solutions