o.c.trends.databrowser2.opiwidget: Display message when no *.plt
filename

Makes it more obvious why the widget doesn't show anything at runtime.
o.c.trends.databrowser2(.opiwidget): Resolve macros for archived data.

PV name macros were not resolved when used as opiwidget.
o.c.trends.databrowser2: Macros in axes labels

Used to show up as $(macro). Now they are resolved at runtime.
.gitignore: Generated jython classes