Support primary constructors

[thekid]

Builds on xp-framework/ast#63 and adds primary constructor support to the compiler.

Examples

Temperature:

use lang\IllegalArgumentException;

class Temp(
  public private(set) float $celsius= 100 {
    set {
      if ($value < -273.15) {
        throw new IllegalArgumentException($value.' is below absolute zero');
      }
      $this->celsius= $value;
    }
  }
) { }

$ xp -w 'new Temp(celsius: -300)'
Uncaught exception: Exception lang.IllegalArgumentException (-300 is below absolute zero)
  at Temp::$celsius::set(-300) [line 6 of Temp.php]
  at Temp::__construct(-300) [line 1 of (command line argument)]
  at <main>::include((0x17)'(command line argument)') [line 163 of Code.class.php]
  at xp.runtime.Code::run(array[1]) [line 30 of Dump.class.php]
  at xp.runtime.Dump::main(array[1]) [line 399 of class-main.php]

Ranges:

class Range(public readonly int $start, public readonly int $end) implements IteratorAggregate {

  public function getIterator(): Traversable {
    if ($this->start > $this->end) {
      for ($i= $this->start; $i >= $this->end; $i--) yield $i;
    } else {
      for ($i= $this->start; $i <= $this->end; $i++) yield $i;
    }
  }
}

$ xp -w '[...new Range(10, 1)]'
[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]