RFC: Improved error messages

I took a crack at improving more error messages.  I also tweaked the formatting of them a bit.  Now only the error message and the affected functions are red. Everything else is the normal color.  This helps the important information stand out.  

Still outstanding is the exception handling.  Right now, exception messages are not being handled consistently, and it would take more extensive changes to make that happen, so I didn't touch them.

Let me know if this is the right direction.

See #4762 and #4744