Set domain of x to [0.5,3]
Set domain of v and w to [0.5,4]
Remove diagnostics from answer checker
Merge pull request #92 from paulvojta/master

Convert to using number_list_cmp instead of asking for the averages of the lists of numbers
% -> $PERCENT
New stat problem.
Small error fixed.
Add units and use built-in $PI.
Fix typo.
Fix bug 3205
Fix bug 3203
Fix bug 3202
Added solutions (adapted from eliminated duplicate problems)
Fix bug 3214, alignment
Fix bug 3213, wrong answer
Fix bug 3217, wording
Make sure the function is not constant.
Added clarification:  sides --> sides of the base
Fix bug 3219, one part of answer is wrong
Added link for interval notation.