Teach "git diff -p" Python funcname patterns

Find classes, functions, and methods definitions.
Signed-off-by: NKirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/gitattributes.txt

@@ -316,6 +316,8 @@ patterns are available:
 
 - `pascal` suitable for source code in the Pascal/Delphi language.
 
+- `python` suitable for source code in the Python language.
+
 - `ruby` suitable for source code in the Ruby language.
 
 - `tex` suitable for source code for LaTeX documents.

diff.c

@@ -1394,6 +1394,7 @@ static struct builtin_funcname_pattern {
 			},
 	{ "bibtex", "\\(@[a-zA-Z]\\{1,\\}[ \t]*{\\{0,1\\}[ \t]*[^ \t\"@',\\#}{~%]*\\).*$" },
 	{ "tex", "^\\(\\\\\\(\\(sub\\)*section\\|chapter\\|part\\)\\*\\{0,1\\}{.*\\)$" },
+	{ "python", "^\\s*\\(\\(class\\|def\\)\\s.*\\)$" },
 	{ "ruby", "^\\s*\\(\\(class\\|module\\|def\\)\\s.*\\)$" },
 };