Python plugin: added pygrep command, simplified pyclean

plugins/python/python.plugin.zsh

@@ -2,4 +2,7 @@
 alias pyfind='find . -name "*.py"'
 
 # Remove python compiled byte-code
-alias pyclean='find . -type f -name "*.py[co]" -exec rm -f \{\} \;'
+alias pyclean='find . -type f -name "*.py[co]" -delete'
+
+# Grep among .py files
+alias pygrep='grep --include="*.py"'