Now ofRectangle::ScaleToMe.  
More scaling options via ofRectScaleMode.

…rks into ofRectangle_Additions

…are based on Qt and could, if desired, be combined into a single bit-wise combined alignment flag.

- x/y are now references to an underlying ofPoint
  for easier ofPoint/ofVec manipulations of an ofRectangl.
  (addresses issue openframeworks#821 by @danomatika)
- Added setters for x/y/width/height/position (vec)
- Changed the variable names on translateXXX to dx/dy (delta x/y)
- Added translateX, translateY
- Added scaleWidth / scaleHeight for independent control.
- changed scaleToMe to simply be scaleTo.
  + remove personal pronoun.
  + Scales itself, rather than returning the scaled version of another ofRectangle.
- Added scaleTo functions that are more generic, using the new ofAspectRatioMode.
  + This allows more flexible scaling with alternate alignments.
  + Overridden functions provide easier access w/o changing defaults.
- Added alignTo functions that now work with the new ofAlignHorz and ofAlignVert enums.
  + contain functions for aligning to other rects, points, and a single value,
    based on a the anchor.
- Moved the overridden operators to the bottom of the implementation file / header.
- Added getLeft()/getRight()/getTop()/getBottom().
  + since our ofRectangle class supports negative width/height, these offer
    more intuitive interaction with known edges.
- Added getHorzAnchor() / getVertAnchor() to get edges by using the new alignment enums.  Throws errors if the alignment enums are invalid.
- getPosition and getPositionRef added.
- Moved getCenter() to live with the other getters.

…rks into ofRectangle_Additions

    ofPoint getTopLeft() const;
    ofPoint getTopRight() const;
    ofPoint getBottomLeft() const;
    ofPoint getBottomRight() const;

…resses openframeworks#1568.  To do much more with lines, we need a `ofLine` - or `ofLineSegment` to make returns easier.  For instances, `ofLineSegment ofRectangle::getIntersection(const ofLineSegment& line);`

…rks into ofRectangle_Additions

…rks into ofRectangle_Additions

…rks into ofRectangle_Additions

…e example are changed to match.

… of the dimensions width/height will never be implicitly modified during member method execution, with the single exception of the explicit `standardize` methods.