Distorted Android

Dynamic display of bounding rectangles (with coords computed by Vertex Shader and gotten with Transform Feedback) works now.

Major problem: the glMapBufferRange() slows doewn rendering in a major way. Multiblur's FPS:

Nexus5X : 35.4 before -> 12.6 after...

Make the Feedback APP work again.

Revert "Progress with TransferFeedback app - introduce two modes: USEPOINTS 'true' or 'false'."

This reverts commit 21304c55380460c5882b789ea13eb00ffd9a686c.

Revert "This commit (and reading the OpenGL ES 3.0 spec) pretty conclusively proves that, sadly, Nexus 4's Transform Feedback implementation is incomplete (doesn't work with GL_TRIANGLES primitiveMode)"

This reverts commit 5ba19814852de1762e452662a13c4944792014a9.

Revert "Some progress with Transform Feedback. Still many bugs all over."

This reverts commit 79921db22e4ff5a3b2e6e3466a39445f5607a695.

Some progress with Transform Feedback. Still many bugs all over.

This commit (and reading the OpenGL ES 3.0 spec) pretty conclusively proves that, sadly, Nexus 4's Transform Feedback implementation is incomplete (doesn't work with GL_TRIANGLES primitiveMode)

Progress with TransferFeedback app - introduce two modes: USEPOINTS 'true' or 'false'.

On Nexus5X, it works with 'true' and 'false'. On Nexus 4, it works with 'true', but returns GL_INVALID_OPERATION with 'false'.

Progress with moving the Transform Feedback functionality from the APP to the library.

Simplifications.