Implement email template generation

Variables are surrounded by {}, and initial (default) templates are
generated on demand from the plaintext version of emails. The custom
emails are intended to only be used if the user actually changes them,
as they lose the features of the default ones, such as tables.

pwreset.go

@@ -81,7 +81,7 @@ func pwrMonitor(app *appContext, watcher *fsnotify.Watcher) {
 						return
 					}
 					address = addr.(string)
-					msg, err := app.email.constructReset(pwr, app)
+					msg, err := app.email.constructReset(pwr, app, false)
 					if err != nil {
 						app.err.Printf("Failed to construct password reset email for %s", pwr.Username)
 						app.debug.Printf("%s: Error: %s", pwr.Username, err)