Improving package pattern matching

[MattTuttle]

Improving package pattern matching so that it more closely matches what Haxe allows.

• Numbers are allowed as long as the package doesn't start with them.
• Periods are not allowed at the beginning or end of packages.
• An empty package can be denoted with package; not requiring a space between package and the semicolon.

  Valid patterns

package;
package foo;
package foo.bar.baz;
package foo1.bar;

Invalid patterns

package foo.bar.;
package foo.2bar;
package .foo.bar;

Interestingly enough even GitHub gets it wrong...

[clemos]

Great thanks !