Make the interacting color orange

Summary:
I couldn't find a color that looked good, so

Test Plan:
Play around with [this item](http://localhost:9000/test.html#content=%7B%22question%22%3A%7B%22content%22%3A%22%5B%5B%E2%98%83%20transformer%202%5D%5D%5Cn%5Cn%5B%5B%E2%98%83%20interactive-graph%201%5D%5D%22%2C%22images%22%3A%7B%22https%3A%2F%2Fka-perseus-graphie.s3.amazonaws.com%2Fda8df81c78b22f5c69d477d8eabfb583968eaf84.png%22%3A%7B%22width%22%3A400%2C%22height%22%3A70%7D%2C%22https%3A%2F%2Fka-perseus-graphie.s3.amazonaws.com%2Fb59fc02ca1aae800977b8793ed22f647a1aa75ee.png%22%3A%7B%22width%22%3A425%2C%22height%22%3A150%7D%7D%2C%22widgets%22%3A%7B%22transformer%202%22%3A%7B%22type%22%3A%22transformer%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22starting%22%3A%7B%22shape%22%3A%7B%22type%22%3A%22polygon-3%22%2C%22coords%22%3A%5B%5B2%2C2%5D%2C%5B2%2C6%5D%2C%5B7%2C2%5D%5D%7D%2C%22transformations%22%3A%5B%5D%7D%2C%22graphMode%22%3A%22interactive%22%2C%22listMode%22%3A%22dynamic%22%2C%22tools%22%3A%7B%22translation%22%3A%7B%22enabled%22%3Atrue%2C%22required%22%3Afalse%2C%22constraints%22%3A%7B%7D%7D%2C%22rotation%22%3A%7B%22enabled%22%3Atrue%2C%22required%22%3Afalse%2C%22constraints%22%3A%7B%22fixed%22%3Afalse%7D%2C%22coord%22%3A%5B1%2C6%5D%7D%2C%22reflection%22%3A%7B%22enabled%22%3Atrue%2C%22required%22%3Afalse%2C%22constraints%22%3A%7B%22fixed%22%3Afalse%7D%2C%22coords%22%3A%5B%5B2%2C-4%5D%2C%5B2%2C2%5D%5D%7D%2C%22dilation%22%3A%7B%22enabled%22%3Atrue%2C%22required%22%3Afalse%2C%22constraints%22%3A%7B%22fixed%22%3Afalse%7D%2C%22coord%22%3A%5B6%2C6%5D%7D%7D%2C%22drawSolutionShape%22%3Atrue%2C%22gradeEmpty%22%3Afalse%2C%22graph%22%3A%7B%22range%22%3A%5B%5B-10%2C10%5D%2C%5B-10%2C10%5D%5D%2C%22step%22%3A%5B1%2C1%5D%2C%22markings%22%3A%22grid%22%2C%22labels%22%3A%5B%22x%22%2C%22y%22%5D%2C%22backgroundImage%22%3A%7B%22url%22%3Anull%2C%22scale%22%3A1%2C%22bottom%22%3A0%2C%22left%22%3A0%7D%2C%22showProtractor%22%3Afalse%2C%22showRuler%22%3Afalse%2C%22rulerLabel%22%3A%22%22%2C%22rulerTicks%22%3A10%2C%22gridStep%22%3A%5B1%2C1%5D%2C%22snapStep%22%3A%5B0.5%2C0.5%5D%7D%2C%22version%22%3A1.2%2C%22correct%22%3A%7B%22transformations%22%3A%5B%5D%2C%22shape%22%3A%7B%22type%22%3A%5B%22polygon-3%22%5D%2C%22coords%22%3A%5B%5B2%2C2%5D%2C%5B2%2C6%5D%2C%5B7%2C2%5D%5D%2C%22options%22%3A%5B%7B%7D%5D%7D%7D%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%2C%22interactive-graph%201%22%3A%7B%22type%22%3A%22interactive-graph%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22step%22%3A%5B1%2C1%5D%2C%22backgroundImage%22%3A%7B%22url%22%3Anull%2C%22scale%22%3A1%2C%22bottom%22%3A0%2C%22left%22%3A0%7D%2C%22markings%22%3A%22graph%22%2C%22labels%22%3A%5B%22x%22%2C%22y%22%5D%2C%22showProtractor%22%3Afalse%2C%22showRuler%22%3Afalse%2C%22rulerLabel%22%3A%22%22%2C%22rulerTicks%22%3A10%2C%22range%22%3A%5B%5B-10%2C10%5D%2C%5B-10%2C10%5D%5D%2C%22graph%22%3A%7B%22type%22%3A%22linear%22%7D%2C%22correct%22%3A%7B%22type%22%3A%22linear%22%2C%22coords%22%3Anull%7D%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%7D%7D%2C%22answerArea%22%3A%7B%22type%22%3A%22multiple%22%2C%22options%22%3A%7B%22content%22%3A%22%22%2C%22images%22%3A%7B%7D%2C%22widgets%22%3A%7B%7D%7D%2C%22calculator%22%3Afalse%7D%2C%22itemDataVersion%22%3A%7B%22major%22%3A0%2C%22minor%22%3A1%7D%2C%22hints%22%3A%5B%5D%7D)

Auditors: eater, charlie