Make problem more concise

There is no need to assume X is not zero.
Merge pull request #125513 from mauk81/unify

color equation in the same way
We can finally kill off the old horrible calculus stuff!

Test Plan:
grep calculus exercises/*.html to verify nothing else uses it
Test derivative_intuition and lhopitals_rule to see that they still work.
special_derivatives is now implemented in Perseus

Auditors: joel
Fix calculator display bug when zoomed in/out

Test Plan: Load an exercise that uses the calculator like http://exercises.ka.local/exercises/law_of_cosines.html and hit cmd-+/- to change zoom levels. Verify the button labels no longer wrap.

Auditors: joel
Remove "typically" for clarity

Reviewers: benjaminhaley

Reviewed By: benjaminhaley

CC: elizabeth

Differential Revision: http://phabricator.khanacademy.org/D5395
lint

Test Plan: tools/runlint.py from webapp (make lint in khan-exercises isn't good enough?)

Auditors: joel
Set the right kline on module load

I really need to refactor this to get rid of all the globals :\  I'm starting to think things were better when it was just lint-blacklisted and I was blissfully ignorant.

Test Plan: none

Auditors: joel
Compare the correct number; also account for machine imprecision just in case

Test Plan: Verify comparing_improper_fractions_and_mixed_numbers accept the correct answers for both problem types.

Auditors: peter
Exercise packer should treat guess like a var

Test Plan: Test packed exercises in local mode that compute guess in a function:
http://exercises.ka.local/exercises-packed/views_of_a_function.html?debug&problem=graph-to-table
http://exercises.ka.local/exercises-packed/derivative_intuition.html

Auditors: alpert
Show correct denominator in hint

Test Plan: Verify hints show the correct denominator

Auditors: peter
fix typo, fix #126023
Merge pull request #127166 from mauk81/patch-2

fix typo, fix #126023
removed unnecessary comma
Merge pull request #117850 from bolin-hsu/concise

Remove irrelevant text from problem
Merge pull request #127579 from mauk81/jslint

removed unnecessary comma
I18nize gcf.

Test Plan:
Loaded http://localhost:8080/math/arithmetic/factors-multiples/greatest_common_divisor/e/greatest_common_divisor
and did a problem taking all the hints, making sure that it displays as before (but showing gcf not gcd)

Auditors: eater
Changed \text to \operatorname to take care of nit.

The spacing seemed the same on this either way, but to be more proper I have changed it.

Test Plan:
Loaded http://localhost:8080/math/arithmetic/factors-multiples/greatest_common_divisor/e/greatest_common_divisor
and did a problem taking all the hints, making sure that it displays as before (but showing gcf not gcd)

Auditors: alpert
CC: eater
remove typo

oops, had put that in while testing out spacing differences

Test Plan:
cross-fingers

Auditors: alpert
Merge pull request #128336 from petercollingridge/division

Fix divider hint
Improve hint counts
Fix how hints are counted

close #218336
fix #126549; fix #128535
Mark string for translation

Test Plan: none

Auditors: peter