change from SpelMessages to SpelMessage. Changed exception getter to getMessageCode() from getMessageUnformatted

updates for Binding code - able to retrieve the type descriptor for a property and ask detailed questions (eg getAnnotations())

changed to [] from {} for projection and selection (including first and last selection).  addresses the problem of clashes with template prefix/suffix

SPR-5673: more intelligence in TemplateAwareExpressionParser.  Supports prefix/suffix escaping and nesting of prefixes/suffixes

more tests - about 82% coverage now.  focused on testing reflection helper since it is rather complex.  some asserts also added.

Fixed StandardTypeLocator to only know about java.lang.* out of the box.  Doc fixes related to that.

objects flowing around in expression evaluation are now TypedValue's - these carry generics info, used for conversions.

design change - no longer surfacing typeDescriptor through property accessor.  conversion done internally in property write() code