Add new compiler config "warningsAreErrors".

[hgschmie]

This adds a new boolean option to the CompilerConfiguration which turns
all warnings from the compiler into errors. For javac and derived
compilers, this is done by adding the -Werror flag in JDK 7 and later.

[hgschmie]

ping?

[hgschmie]

bump

[agudian]

I just wanted to take a look and merge it, but I get a test-failure (on windows):

Running org.codehaus.plexus.compiler.javac.ErrorMessageParserTest Tests run: 11, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.048 sec <<< FAILURE! - in org.codehaus.plexus.compiler.javac.ErrorMessageParserTest testCRLF_windows(org.codehaus.plexus.compiler.javac.ErrorMessageParserTest) Time elapsed: 0.019 sec <<< FAILURE! junit.framework.AssertionFailedError: count expected:<3> but was:<4> at junit.framework.Assert.fail(Assert.java:47) at junit.framework.Assert.failNotEquals(Assert.java:280) at junit.framework.Assert.assertEquals(Assert.java:64) at junit.framework.Assert.assertEquals(Assert.java:198) at org.codehaus.plexus.compiler.javac.ErrorMessageParserTest.testCRLF_windows(ErrorMessageParserTest.java:625) 

Could you please take a look? And perhaps rebase to the latest head...

[rfscholte]

I've added the option failOnWarning which is a parameter used by other plugins as well. This change supersedes this request.