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.
Updates made to heat flow lab.
Merge branch 'develop' into heat_flow

Merge with develop
Typo fix.
Clarification of problem 2/minor edits
Modified first two finite difference labs.
Clarification/reminders to see documentation
Merge branch 'develop' of https://github.com/byuimpactrevisions/numerical_computing into develop
Beginning update of Hysteresis lab.
Further modifications to the Hysteresis lab.
Further modifications to Hysteresis lab.