Fix data type of "general.firstdayofweek"

This option wasn't converted to a proper data type when it was renamed
from "week_begins_on_monday" to "general.firstdayofweek". Convert the
boolean option into an enumeration type that can take the values
"monday" and "sunday". Also, update the documentation, add a conversion
rule to the upgrade script and convert the configuration file used in
the test suite.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

scripts/calcurse-upgrade

@@ -68,6 +68,7 @@ if grep -q -e '^auto_save=' -e '^auto_gc=' -e '^periodic_save=' \
   BEGIN { FS=OFS="=" }
   $1 == "general.systemdialogs" || $1 == "general.progressbar" \
     { $2 = ($2 == "yes") ? "no" : "yes" }
+  $1 == "general.firstdayofweek" { $2 = ($2 == "yes") ? "monday" : "sunday" }
   { print }
   ' < "$CONFFILE" > "$tmpfile" || exit 1
   mv "$tmpfile" "$CONFFILE" || exit 1