Merged from trunk -r14250:14256

   Merged from trunk -r14250:14256

   | 14251   | Simplify the _pkg regex and fix validation for some cases by |
   | zmedico | using the _version regex to match unwanted version-like      |
   |         | components which can not be at the end of a _pkg match. For  |
   |         | example isvalidatom('app-doc/php-docs-20071125-r2') now      |
   |         | correctly returns False.                                     |

   | 14252   | Simplify isvalidatom() to simply use the Atom class. Thanks  |
   | zmedico | to Marat Radchenko <marat@slonopotamus.org> for the          |
   |         | suggestion.                                                  |

   | 14253   | Add more test cases.                                         |
   | zmedico |                                                              |

   | 14254   | Use the Atom class to implement dep_getkey(), and fall back  |
   | zmedico | to legacy code when necessary for backward compatibility.    |

   | 14255   | Make isspecific() use the Atom class and fall back to legacy |
   | zmedico | code if the atom is invalid. Also, optimize called           |
   |         | isjustname() legacy code to only check the last 2            |
   |         | components.                                                  |

   | 14256   | Make get_operator() use Atom, and remove unnecessary         |
   | zmedico | reflection code from dep_getkey(). Thanks to Marat Radchenko |
   |         | <marat@slonopotamus.org> for suggestions.                    |

svn path=/main/branches/prefix/; revision=14260