Partial support for Ada 2005 features in gnatpp
A new -gnat05 option is added to gnatpp. When called with this option, gnatpp can process Ada sources containing some Ada 2005 features:

  - overriding indicators
  - null subprograms
  - interface types
  - generalized anonymous access types
  - null exclusion
  - tagged incomplete types
  - limited aggregates ('<>' in component associations)
  - subprogram calls given in Object.Operation notation
  - limited and private with clauses
  - raise with string message
  - formal abstract subprograms
  - partial parameter lists for formal packages

A future gnatpp version will fully support Ada 2005.