Write errors to an error log

[dyoung522]

At default verbosity, we should not list all errors produced -- can be quite lengthy and obscure which tiles need to be re-built.

• We should write all errors to an error log, which the user can manually check after each run if they so desire.
• Increased verbosity should show the errors on screen, but still write them to a log file.
• There should be an option to provide the log path and name
• there should be an option to skip the log creation (e.g. --no-log)