improve formatting by removing backslash.
Merge pull request #50 from Dick-Lane/master

revise tagging for 5 problems and fix 1
Fix bug 2849.
New version of an indeterminate limit problem. MLT added to old probem.
MLT tag added.
Fix bug 2853.
Reword problem text and fix custom answer checker

Problem text now includes a particular point for the "stopping time" of the parametrization.

Answer checker updated to correct coding errors from when I was still learning how to use MathObjects in custom answer checkers.
Use custom answer checker to allow multiple correct answers
New lin alg problems.
Minor fix.
New linear algebra problem.
Merge branch 'master' of github.com:openwebwork/webwork-open-problem-library
correct domain for log checking.
New optimization problem.
Small fix.
Add clarifying instructions to problem text

(in millions of barrels per day)
Small fix.
Merge branch 'master' of git://github.com/openwebwork/webwork-open-problem-library
Add "no real solutions" to problem text.
Add "no real solutions" to problem text.