Prevent double encoding of 
 
 	 characters

[neilcampbell]

Fixes #26

Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

[codecov-commenter]

Codecov Report

Merging #27 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master      #27   +/-   ##
=======================================
  Coverage   99.21%   99.21%           
=======================================
  Files          17       17           
  Lines        1902     1902           
  Branches      503      503           
=======================================
  Hits         1887     1887           
  Misses         15       15           

Impacted Files	Coverage Δ
src/builder/XMLBuilderCBImpl.ts	98.70% <100.00%> (ø)
src/writers/BaseWriter.ts	97.46% <100.00%> (ø)

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[oozcitak]

Thank you for the PR. There are only five special characters defined in the XML Spec: > < & " '. So this library limits itself to those five.

I am fine with xmlbuilder2 being used in other markup languages. But in that case, I would prefer such additional functionality to be provided by adding flags or custom functions instead of changing base behavior. In that case, that would be custom text and attribute serialization functions that would be passed to the end function. Or maybe a flag that would change serialization behavior when set.

Also please see: #17
Custom functions in old xmlbuilder: https://github.com/oozcitak/xmlbuilder-js/wiki/Value-Conversion#textescape-functionstr

[neilcampbell]

@oozcitak I'm using it to build xml, however the xml I am generating needs to exactly match a format produced by a different xml library in a different language. I think I'll just regex replace the xmlbuilder2 output, as currently there is no way for me to add encoded new line characters in attribute values without double encoding happening.