Some spacing changes.
Restructured line breaks in the weight loss tex file.
Standardized labels in the wloss lab.
Revised style of example code in wloss lab.
Fixed undefined references.
More code formatting fixes and some typo fixes.
Basic editing pass on the SIR lab.
Reformatted spacing and line breaks in SIR lab.
Clarified time stepping in last problem of SIR lab.
Clarified some redundant sentences and fixed a bad link.
Typo fix.
Merge pull request #592 from insertinterestingnamehere/wloss

Wloss
Merge pull request #590 from insertinterestingnamehere/sir

Edits to the SIR lab.
Merge branch 'develop' of https://github.com/byuimpact/numerical_computing into develop