Remove deprecated Qgis::WKBType and API cleanup (#3325)

* Remove deprecated Qgis::WKBType and API cleanup

Renames QgsWKBTypes to QgsWkbTypes

Replaces usage of the enums:

* Qgis::WKBType with QgsWkbTypes::Type
* Qgis::GeometryType with QgsWkbTypes::GeometryType

Their values should be forward compatible (a fact that was already
explited up to now by casting between the types)

Renames some SSLxxx to SslXxx and URIxxx to UriXxx

* Fix build warnings and simplify type handling

* Add a fixer to rewrite imports

* The forgotten rebase conflictThe forgotten rebase conflicts

* QgsDataSourcURI > QgsDataSourceUri

* QgsWKBTypes > QgsWkbTypes

* Qgis.WKBGeom > QgsWkbTypes.Geom

* Further python fixes

* Guess what... Qgis::wkbDimensions != QgsWkbTypes::wkbDimensions

* Fix tests

* Python 3 updates

* [travis] pull request caching cannot be disabled

so at least use it in r/w mode

* Fix python3 print in plugins