#36 #50 #52 - added frame() & popup(), fixed snap() & read()

oops, missed out 1 line when pushing previous commit. somehow that line in snap() wasn't selected to push.

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#36 - add link to license in tagui.py to facilitate air-gap deployments (without internet access to pip)

#50 - add frame() function to access web page frames (supports main frame and sub frame). add popup() function to access webpage popup tabs launched from webpage.

#52 - bugfix for snap() and read(), when 'page' is used to mean entire webpage a 'cannot find page' error message appears.

tagui.py

@@ -944,6 +944,7 @@ def snap(element_identifier = None, filename_to_save = None, test_coord1 = None,
                     element_identifier = element_identifier + coord(test_coord1, test_coord2)
                     filename_to_save = test_coord3
 
+    if element_identifier.lower() != 'page' and not exist(element_identifier):
         print('[TAGUI][ERROR] - cannot find ' + element_identifier)
         return False