JBIDE-15493 - cleanup classpath.core to properly segment internal vs
public api

JBIDE-15392 slightly-related cleanup of the api. Specifically, move classes that should be internal into itnernal package

JBIDE-15392 additional api enhancement for the usecase of no IRuntime, just a server home

JBIDE-15392 fixing test suite for failing tests

JBIDE-15392 - modified to work with recent changes for JBIDE-15478

JBIDE-15392 - further work on failing unit tests, enhancing unit tests,
fixing regressions (not all returned paths were absolute), etc.

JBIDE-15392 - small further cleanup, api filters, headers, etc

JBIDE-15392 removing new api classes and test
Revert "JBIDE-15392 removing new api classes and test"

This reverts commit afcafe4d70a28a5b155b042246d886639cf93b03.