Fix the way paramters are handled

[mchesser]

Fixes #3 by special casing parameters of the form $n/${n} where n <= 9 and $@/${@}

[codecov-io]

Codecov Report

Merging #4 into master will decrease coverage by 0.22%. The diff coverage is 96.77%.

@@            Coverage Diff             @@
##           master       #4      +/-   ##
==========================================
- Coverage   99.43%   99.21%   -0.23%     
==========================================
  Files           4        4              
  Lines         356      380      +24     
==========================================
+ Hits          354      377      +23     
- Misses          2        3       +1

Impacted Files	Coverage Δ
src/converter_test.rs	100% <100%> (ø)	:arrow_up:
src/converter.rs	98.52% <92.3%> (-0.71%)	:arrow_down:

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[sagiegurari]

@mchesser loved it. Can we somehow merge that duplicate code to a single function called from both replace functions? that would help improve those cases when needed.

[mchesser]

@sagiegurari Yeah makes sense -- I've updated the PR

[sagiegurari]

looks good! merging it in. i'll publish it soon, after i write few more tests around this. thanks a lot