Support Incremental Analysis Cache

[lonelyma1021]

SInce the pmd support cache, why not add this function to eclipse-plugin. It is useful for us, since our project is very huge, it will takes about 10 minits to check the whole project(our ruleset contains about 150 rules).

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Currently, the Eclipse plugin runs PMD analysis as part of the build. This means the build step takes much longer. Instead, PMD should record what files were built and then after the build step completes run a non-blocking PMD step.

(Originally from pmd/pmd#1479)