support for assertEquals([String message, ] CharSequence, CharSequence)

This contribution fixes a problem I've run into when using assertEquals on two CharSequence.

It basically already works, of course - BUT one is left wondering why e.g. the Eclipse (and presumably other IDE as well) JUnit view's Result Comparison pop-up does not work on double-clicking a failure.. this is because, currently, assertEquals on two CharSequence throws only a generic AssertionFailedError and not the ComparisonFailure expected by such UIs.

PS: As the pom.xml specifies jdk.version 1.5 and <compilerVersion>1.5</compilerVersion>,  I was assuming, hopefully correctly, that introducing a @since 1.4 CharSequence was not a problem for backward compat.
Really? But there are lots in https://github.com/junit-team/junit/search?p=1&q=%22%40author%22&ref=cmdform .. ah, you probably mean it's OK only class level, and not method? OK, fine - I've removed (4x) those in https://github.com/vorburger/junit/commit/fe417de17568211b27de9ac8d7e616ff5ef26bb1. Is the contribution acceptable if I leave just the one in src/test/**/org.junit.tests.assertion.AssertionTest.charSequence()  - only for my grandchildren to see that I've contributed to JUnit, when they'll learn Java? ;-) Else I'll remove that too.