* [Diagnostics] Turn educational notes on-by-default
* [Diagnostics] Only include educational notes in printed output if -print-educational-notes is passed
* Make -print-educational-notes a driver option
* [Diagnostics] Issue a printed remark if educational notes are available, but disabled
* [docs] Update educational notes documentation and add a contributing guide
* [Diagnostics] Cleanup PrintingDiagnosticConsumer handling of edu notes
* Revert "[Diagnostics] Issue a printed remark if educational notes are available, but disabled"
For now, don't notify users if edu notes are available but disabled. This decision can be reevaluated later.
* [Diagnostics] Experimental diagnostic printing updates
This new style directly annotates small snippets of code with
error messages, highlights and fix-its. It also uses color more
effectively to highlight important segments.
* [Diagnostics] Stage educational notes and experimental formatting behind separate frontend flags
educational notes -> -enable-educational-notes
formatting -> -enable-experimental-diagnostic-formatting
* [Diagnostics] Refactor expensive line lookups in diag formatting
* [Diagnostics] Refactor some PrintingDiagnosticConsumer code into a flush method
* [Diag-Experimental-Formatting] Custom formatting for Xcode editor placeholders
* [Diag-Experimental-Formatting] Better and more consistent textual description of fix its
* [Diags-Experimental-Formatting] Handle lines with tab characters correctly when rendering highlights and messages
Tabs are converted to 2 spaces for display purposes.
* [Diag-Experimental-Formatting] Refactor byte-to-column mapping for efficiency
* [Diag-Experimental-Formatting] Fix line number indent calculation
* [Diag-Experimental-Formatting] Include indicators of insertions and deletions in the highlight line
Inserts are underlined by green '+' chars, deletions by red '-' chars.
* [Diag-Experimental-Formatting] Change color of indicator arrow for non-ASCII anchored messages
* [Diag-experimental-formatting] Make tests less sensitive to line numbering
* [Diag-Experimental-Formatting] Update tests to allow windows path separators
* [Diag-Experimental-Formatting] Bug fixes for the integrated REPL
