remove deprecated functions for 0.8.0, closes #1428

This PR removes functions which have been deprecated since 0072.

The removed functions are:

`ofVec*f::squareLength()`
`ofVideoGrabber::grabFrame()`
`ofVideoPlayer::idleMovie()`
`ofPolyline::addVertexes` 
`ofGraphics: ofVertexes` and `ofGraphics: ofCurveVertexes` 
`ofQTKitPlayer::bind() and ofQTKitPlayer::unbind()`
`ofAppiPhoneWindow::enableRetinaSupport()`, `ofAppiPhoneWindow::isRetinaSupported()` and `ofAppiPhoneWindow::isDepthEnabled()`