modularisation part 1: scala-xml and scala-parser-combinators

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• scala.util.parsing --> scala-parser-combinators.jar
• scala.xml --> scala-xml.jar (needed when compiling embedded xml snippets)

as discussed here: https://groups.google.com/d/topic/scala-internals/axzOQ6fUNQg/discussion

there will be docs to aid in the transition here: https://github.com/scala/scala/wiki/Scala-2.11

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Imported From: https://issues.scala-lang.org/browse/SI-6811?orig=1
Reporter: @adriaanm

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@retronym said:
One small but important point it to have build infrastructure in place for unified scaladoc.

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@adriaanm said:

• json
• scala.util.parsing
• xml (+automata)
• collections views
• scala.sys

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@soc said:
The removal part starts here: scala/scala#1921

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@soc said:
Adriaan intends to split parsers into a separate jar file: scala/scala#2581 (comment)

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@soc said:
Split scala.util.parsing and move it to its own jar: scala/scala#2661