[PATCH] JXR Comment handling has several shortcomings

I have identified the following issues:

• a // comment does not properly mask a subsequent /* on the same line.
• explicitly tries not to terminate comments if */ is embedded in a string, but compilers don't behave this way.
• does not handle /*/ construct properly: recognized as javadoc but not terminated, while it is better interpreted as /[empty]*/.

I have addressed these issues + JXR-58 by reworking the comment handling code. Formerly the filters were applied

; my version of the code uses

specifically to address the first of the issues noted above. I was unable to find any exhaustive tests for this code; please guide me if there is any further testing I can provide. I have collapsed the duplicate code in these regions as much as possible, and since this project is on maven-parent v21 I believe I was justified in replacing the StringBuffers in affected areas with StringBuilders (obviously the whole file might benefit minutely from this treatment).