Decode input characters and encode output using provided Charset

[MikeEdgar]

Fixes #33

Calling flush() (or close()) on the EDIStreamWriter is critical with this change due to the buffer used by OutputStreamWriter.

[coveralls]

Pull Request Test Coverage Report for Build 115250475

• 59 of 62 (95.16%) changed or added relevant lines in 7 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.07%) to 95.287%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/io/xlate/edi/internal/stream/tokenization/Lexer.java	35	36	97.22%
src/main/java/io/xlate/edi/internal/stream/StaEDIStreamWriter.java	10	12	83.33%

Totals
Change from base Build 112952905:	0.07%
Covered Lines:	3700
Relevant Lines:	3883

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💛 - Coveralls

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

96.0% Coverage
0.0% Duplication

[MikeEdgar]

@ChrisPaprocki - these changes should be release later this week.