Annotation manager moved to dart (#779)

* line annotations in dart

* working drag

* add ios drag support

* added other annotation managers

* support old api with new managers

* ios remove annotations

* web cleanup

* working android version

* fixed symbol text issues

* fixed fill pattern issue

* added support for symbol allow overlap

* working android drag

* fixed ios issues

* added source#setFeature to iOS

* added setGeoJsonFeature to android

* add support for dragEnabled

* added option to toggle interaction for layers

* fixed web issue with textFont

* removed unused imports

* better documentation
added missing options to line manager

* revert line example changes

* added a fix for the android performance issues

* improved code for detecting drag starts

* code review changes

* post rebase fixes

* fix build issue with location