Change the interaction of --eol-from-mime-type and --no-default-eol options.

Change the interaction of --eol-from-mime-type and --no-default-eol options.

Previously, the default eol-style of "native" was unconditionally set
on all non-binary files, unless --no-default-eol was specified.
Therefore, the --eol-from-mime-type option was completely ignored
unless the --no-default-eol option was also specified.  This behavior
also prevented having some files' eol-style chosen based on their mime
types, and the files with undefined mime types set to 'native'.

This change gives priority to the --eol-from-mime-type option; if this
option is specified, then it determines the eol-style of all
non-binary files with defined mime types.  Only non-binary files with
undefined mime types are affected by the --no-default-eol option.

* cvs2svn (SVNCommitItem.__init__): Changed algorithm for determining
  eol-style as described above.

  (usage): Document new meanings of options.

* run-tests.py (eol_mime): Test that the behavior matches the new
  expectation.

* cvs2svn.1, cvs2svn.html: Document the new meanings of the options.

git-svn-id: http://cvs2svn.tigris.org/svn/cvs2svn/trunk@1648 be7e6eca-30d4-0310-a8e5-ac0d63af7087