Refine AntPathMatcher.combine when p1 contains '.'

Refine AntPathMatcher.combine rules to allow direct concatenation of
patterns when pattern1 does not contain '*.'. Prior to this commit
direct concatenation was allowed when pattern1 did not contain '.',
this prevented calls of the form:

	pathMatcher.combine("/1.0", "/foo/test")

from working as expected.

This commit also applies some general cleanup to the `combine` method.

Issue: SPR-10554