Fix cursorManager selection bugs. (PR #7131)
- In browse mode, pressing shift+home after selecting forward now unselects to the beginning of the line as expected. (#5746)
- In browse mode, select all (control+a) no longer fails to select all text if the caret is not at the start of the text. (#6909)
- cursorManager: Fix selecting forward, then selecting backward without unselecting, then unselecting forward, and vice versa.
