Convert enumeration MyMoneyReport::EColumnType into a class to be more type safe
Type safety is increased by moving the enum into a separate name space (here
a class is used because namespaces are not allowed inside classes).
Q_ENUM(s) or QFlags could also not be used because the related enums need
to be defined somewhere outside, which does not solve the issue having all
constants in MyMoneyReport namespace.
Test Plan: compiled on linux
Reviewed By: KMyMoney, tbaumgart
Differential Revision: https://phabricator.kde.org/D11043
Signed-off-by: Ralf Habacker <firstname.lastname@example.org>