Unescape dollar signs in single-line strings

[christopher-dG]

Fixes #108

Kind of a naive fix, but it's all we really need. Anything else would require not using repr at all.

[codecov]

Codecov Report

Merging #111 (b6c7a98) into master (31f1911) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #111   +/-   ##
=======================================
  Coverage   83.70%   83.70%           
=======================================
  Files          12       12           
  Lines        1479     1479           
=======================================
  Hits         1238     1238           
  Misses        241      241           

Impacted Files	Coverage Δ
src/writer.jl	98.07% <100.00%> (ø)

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