Add high dose alerts to OpenREM / openSkin

[Debbie Harries]

I think it would be very useful if openSkin/openREM would automatically alert me via email when

1. A dose trigger level (set by me) is exceeded
2. A patient has had more than one procedure within a defined period (set by me)

[Ed McDonagh]

@dplatten - tie this in to issue ref #665?

[Ed McDonagh]

@dplatten - keep this for consideration of alerting based on openSkin, or close with #665?

[David Platten]

I think we should keep this for consideration of alerting based on openSkin.

The skin dose maps are calculated as a background task, so the calculated peak skin dose is not available at the immediate time of import. However, the skin dose map routines could be modified to send an additional alert based on peak skin dose.

[Luuk]

@David Platten implemented trigger levels for dose at reference point and dose area product. These values can be summed over a set period of time. @wens implemented a dose trigger level for skin dose (per study). @Debbie Harries Would that cover your needs (so we can close this issue)?