Added some API methods for viewTags
Added initial version of visual mode
Improvements to moving in visual mode & added comments
Use view.VisualRange instead of view.Tags
Add delete command to visual mode
Added visual line mode
Add `v` and `V` commands to visual mode
Keep visual mode init in the same switch statement
Fix repeating movement in visual mode
Move function to view package
Un-export visualRange
Rename viewTag to Tag
Un-export view.tags
Merge pull request #25 from gchp/visual-mode

Added visual mode