PluginInfo: fix deprecation warning
Move key/value pairs concept to BasicDetails

Previously, the concept was defined only in PluginInfo, but ModuleItem
really needs it too (ImageJ's @Parameter annotation, which ModuleItem
codifies in some sense, allows a list of @Attr elements, just like
SciJava Common's @Plugin annotation does).

The common base for PluginInfo and ModuleItem is BasicDetails (since
those two annotations also share name, label and description), so it is
the natural place to have the key/value pairs, too.
ConversionUtils: use src and dest for consistency

All conversion-related methods that take a source object or type, as
well as a destination type, now refer to the source as "src" and the
target type as "dest". Hopefully, this makes the code more consistent
and easier to understand.
ConversionUtils: add canConvert(Class, Type)

This shadows the convert(Object, Type) method in the same way that
canConvert(Class, Class) shadows convert(Object, Class).
Bump to next development cycle

Signed-off-by: Curtis Rueden <ctrueden@wisc.edu>