Feature request - Integrate calendar w/ external sources like Google or iCalendar feeds

(from [a6d2c0c6a1e5e181412ef56cced986e10f59ee77]) Initial attempt to integrate calendar w/ external sources like Google or iCalendar feeds, only ical working. Also adds 'polished' 2.0 type interface to calendar [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] https://github.com/exponentcms/exponent-cms/commit/a6d2c0c6a1e5e181...

(from [57c604e3f29ef8d58f8583ba8c927f0aa8949679]) Missing iCalendar library [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] https://github.com/exponentcms/exponent-cms/commit/57c604e3f29ef8d5...

(from [4d88e8d44a93b8e46cd64e2a66753d30f1d9e82b]) Implements Google XML calendar integration (can be slow), makes external events inert (no edit/delete/view), adds new expDateTime method endOfDayTimestamp...still need some timezone calculations and is_allday for the iCalendar events. [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] https://github.com/exponentcms/exponent-cms/commit/4d88e8d44a93b8e4...

(from [f286f1ccb87980af45e23ea5707a23671b809ae6]) Fixes some date anomalies, esp w/ default view, recodes show method to use 'switch' statement instead of if/else's. [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] [#605 state:resolved milestone:2.0.7 https://github.com/exponentcms/exponent-cms/commit/f286f1ccb87980af...

(from [3ea899d8fe9dd8a04aeb6dcf87c054fec5f7d2ef]) Removes (comments out) unused item permissions left over from exp 0.9x [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] https://github.com/exponentcms/exponent-cms/commit/3ea899d8fe9dd8a0...

(from [4fd42011ff413bc5b4c4428ffb2eccba5f16f042]) Much more efficient 'external event' algorithm greatly increases speed, but it's still slower than local events; Adds new help methods to expDateTime subsystem [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] https://github.com/exponentcms/exponent-cms/commit/4fd42011ff413bc5...

(from [39e8215e21e0fcc7aaea5192763e08dea83524a9]) Corrects DST issue...not sure we can fix timezone issue on our end as info gets sent as GMT time even though it's in the timezone of the calendar [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] https://github.com/exponentcms/exponent-cms/commit/39e8215e21e0fcc7...

(from [2a74a6c7e7d9af8c51ffe658003608732e404c03]) Provides a cleaner external event link (no href which won't take you to the top of the page) [#468 Feature request - Integrate calendar w/ external sources like Google or iCale...] https://github.com/exponentcms/exponent-cms/commit/2a74a6c7e7d9af8c...