[fix] quick and dirty fix to work around error on macOS Mojave #23

[melbow]

Calling get previously threw up this error:

ERROR PerlObjCBridge:: sendObjcMessage: Can't get NSMethodSignature for message get ERROR PerlObjCBridge: error [1] sending message [NSObject get] at /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level/PerlObjCBridge.pm line 248.

[theory] it seems that, since mojave, PerlObjCBridge tries to look up 'get' method signature on NSObject instead of SBObject,

• which only exists on SBObject (subclass of NSObject). Seems to only happen with AXMainWindow / AXFocusedWindow, not sure if
• key/value of these attributes have changed? anyway, this quick fix at least provides a bandage to get the script working again,
• by overriding calls to get() with a direct call to sendObjMessage with hard-coded 'SBObject' for class name

[melbow]

Haven't tested this on any other OSes than Mojave btw Just tested on 10.12 (Sierra) - seems to still be fine with these changes