Added some string escaping

[RobertoRoos]

Contributes to

• Special characters inside literal strings are not escaped by grammar #29

Following

• Error Parsing Custom Type Declaration #26

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.39%. Comparing base (8801ea1) to head (60c1209).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #30   +/-   ##
=======================================
  Coverage   84.39%   84.39%           
=======================================
  Files          10       10           
  Lines         737      737           
=======================================
  Hits          622      622           
  Misses        115      115           

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[RobertoRoos]

@Philipp1297 only if you'd still like to, but could you test this branch on your string problem?

This fix is far from perfect, but I'm hoping this will catch 80% of practical cases.
And I just learned you could always avoid these issues by using a TwinCAT string constant instead: https://github.com/DEMCON/plcdoc/pull/30/files#diff-e890d65932fde6e97c0ea021ad58ef7aa41e838582f2755f59d0924a70323b0bR45
Of course the goal is to be compatible with all code, but I'll take baby steps.

[Philipp1297]

@RobertoRoos My project is now working without any grammer exceptions.
Thank you for your work!