Show factor tree in two hints regardless of size
New exercises
Improve regex generation
Rename Simplifying rational expressions 4, Linear equations 4
Merge pull request #52187 from mauk81/patch-2

fix plural in problem text, fix #47643
Merge pull request #52272 from mauk81/patch-5

avoiding rounding problem, fix #46111; fix #49683; fix #52739
Merge pull request #52393 from mauk81/congruent

fix wording in geometry_proofs_intro
Merge pull request #53732 from mauk81/patch-1

removed multiple equal sign, fix: #53691
New exercise
Improve hints
Add questions with non-factored expressions
Create function for writing expressions in a factored form
Add extra hint showing factoring
Fix hints with negative numbers and denominator of 1
New exercise
Add functions to generate factored strings
Merge remote-tracking branch 'upstream/master'
Ensure hints correctly expanded
Parenthesise correctly when multiplying by 1
Simplify code