Cleanup BatchRenderer internal names and documentation (#5852) ...

I have edited the BatchRenderer class. The following major changes were
made:

1. Changed old `vertexCount` to `_flushId`. This is because the name
itself was misleading. It signified the number of flushes in the
current frame.

2. Renamed `vaos` and `vaosMax` to `_packedGeometries` and
`_packedGeometryPoolSize`. They _were not_ VAOs in the sense
that they binded all the buffers automatically to the WebGL
context. Instead, they were just reusable `BatchGeometry` objects.

3. Renamed `groups` to `_drawCalls`. That is what they are, and it
makes more sense, especially after documenting it.

4. Renamed all private variables by adding a _ prefix.

5. Added documentation to all private/public properties and methods.

6. Fixed destroy(). It was nullifying non-existent variables. They
were probably from when this class was being built/tested. I've fixed
it so that it nullifies the correct resources.

7. contextChange signal is now hooked in `BatchRenderer` rather than
the `BatchPluginFactory#create`. This makes sense since the former
is the one implementing the `contextChange` signal.

8. SIDE EFFECT: Graphics used the `shader` property of `BatchRenderer`,
and since that was deemed a private properties, it broke. It fixed that
by making Graphics use `_shader`.

9. I reordered the way in which properties are initialized in the
constructor. The most important/public ones are on the top. They are
ordered in a way that makes a new-comer sense.

10. Reordered methods. The first methods are related to rendering and
are lifecycle-type methods: contextChange, render, flush, and destroy. Then
the start and stop methods. Then the private methods getAttributeBuffer,
getIndexBuffer, and packInterleavedGeometry.

11. Renamed packGeometry to packInterleavedGeometry; this is because
the method doesn't take any geometry to put into. Rather it takes
the interleaved buffers.

12. Documented literally anything else.

Fixes Graphics clear fill and line style settings (#5797)

Renames StateSystem.setState to StateSystem.set (#5791)

Graphics documentation and typing fixes (#5544)

Fixes arc duplicating points (#5526)

Fixes Graphics holes on canvas and closePath (#5516)

Fixes Graphics closePath (#5515)

Proper disposal for Mesh and Graphics Geometry objects (#5349)

Documentation updates (#5366)

Fix types in documentation (#5345)

Fixes beginTextureFill and lineTextureStyle usage of Matrix (#5295)

Fixes moveTo and lineStyle (#5221)

Fixed tint / alpha for non-batched Graphics objects (#5217)

Graphics does not depend on Mesh (#5206)

Replaces toJSON with clone in Graphics LineStyle (#5207)

Tweaked graphics to share one default shader (#5205)

fixed alpha for graphics ...

disabled batching for now as I noticed an issue that needs fixing

Fixes with Graphics tinting and premultiply (#5182) ...

* fixed the premultiply issue with graphics

* fixed tinting in webGL graphics

Sprite, Mesh and Graphics refactor to including in batching, Take 2 (#5132)

Revert "[next] Sprite, Mesh and Graphics refactor to including in batching (#5069)" (#5127) ...

This reverts commit 4743491.

[next] Sprite, Mesh and Graphics refactor to including in batching (#5069)

Optimization to Graphics fastRect to cache tint (#5033)

Prevent gaps in duplicate Graphics lineTo calls (#5084) ...

Fixes test

Fixes arc method by not adding an additional point if it's too close to the last existing point. (#5010) ...

As it was the code did check for exact equality of X and Y coordinates. This wasn't sufficient, since extremely small differences still lead to problems further down the line due to floating point inaccuracies.

Don't auto-close paths when using Graphics with CanvasRenderer (#4997) ...

When defining a path, any call to beginFill results in the path being closed,
but only for the Canvas renderer, not for the WebGL renderer.
This commit removes the check that sets the shape to be closed when a fill is
active. This unifies the rendering behavior between Canvas and WebGL.

CanvasRenderer tint could affect bounds calculation (#5028)

Fix Graphics.lineStyle jsdoc (#5026) ...

The default alignement value is 0.5, not 1.

Fixes linting errors

Adds Graphics adaptive calculation of quadratic curve and arc subdivision (#4658)

VAO leak in Mesh and Graphics (#4893)