[log] Allow filtering by method in a PHP class/interface/trait

[aik099]

Sometimes it's interesting to see commits, that changed contents of a particular method in a PHP class/interface/trait instead of just looking for any change in the file.

In most cases, then svn blame command with some manual input (e.g. #116) would do the trick, but in cases, when:

• code was removed (therefore not shown when doing svn blame on HEAD revision)
• you're not quite sure how code looked to use svn-buddy.phar search command
• code to be searched is very common and used in other methods as well

How this can be implemented:

When collecting repository info from log command (aka revision log cache) for affected *.php files also:

1. get classes defined
2. do ReflectionClass to get methods
3. for each method do getStartLine and getEndLine
4. do the blame on a particular revision (or maybe svn cat or svn diff) to see if code between lines where method is declared was changed

Later accept --method option/parameter of log command, that will filter out only revisions where given method was changed.