Fix for [#34099] Particles leaking from moving meshes

This was caused by a floating point precision error. During collision detection, Newton-Raphson iteration is used to find the exact time of the collision. But when using subframes, the initial Newton step was too small. Now the initial step is given in absolute units. When subframes = 0, this should behave almost the same as before.

Thanks to Janne Karhu, Lukas Toenne and Ton Roosendaal for their help with this patch, and to AutoCRC for funding.

Applying sRGB color space transform when baking to vertex colors. Thanks to Campbell Barton and Sergey Sharybin for their help!

Changing units of stiffness parameter in classical (new) SPH solver: used to be speed of sound squared; now just speed of sound.

The classical SPH solver was not in 2.65, so this change is unlikely to affect many users. But beta users who have been trying it out will need to change the stiffness parameter to sqrt(old value).

Fix own mistake in SPH solver selection. Thanks Campbell for pointing it out.

Fix for [#33788] Particles - Fluid "exploding" behavior

Particle mass was being used incorrectly by DDR solver (my fault).

Patch [#29035] Vertex colour baking

There is a new option in the Bake panel to enable baking to vertex colors. Unlike regular baking, this mode does not require a UV map or image to bake to, however the object must have a vertex color layer.

Thanks to:
- AutoCRC for funding
- Brech van Lommel and Dalai Felinto for their initial advice on how to implement it
- Campbell Barton for helping to make this feature work with modifiers and bmesh

Adding a new SPH solver that is more physically accurate. See patch #29681

http://projects.blender.org/tracker/index.php?func=detail&aid=29681&group_id=9&atid=127

The solver was mostly implemented by John Mansour at VPAC, with help from me and with funding from the AutoCRC. The SPH formulation is due to Gingold and Monaghan, and the smoothing kernel is due to Wendland.

This solver does not replace the old one; it is available as an option. Note that the new solver uses different units than the old one. The patch page has a couple of attachments that can be used to test the new solver, particularly sphclassical_dam_s0.01_grav.blend (ignore the earlier tests). The simulation in that file compares well with a physical experimental dam break; details in a paper by Changhong Hu and Makoto Sueyoshi, also referred to on that page.

Can now set a lower bound on the number of subframes (i.e. an upper bound on the time step size) for fluid simulations. Previously, the "subframes" parameter was not available when the adaptive time step was enabled; now they can both be set. The two settings can be used together to greatly increase simulation stability.

Added example of KX_GameObject subclassing to game engine docs.

Fix for aliased fonts in the game engine.
- Mipmaps are generated in BLF when drawing text in-game. In that case, padding around each glyph is increased to prevent bleeding.
- Texture filtering is turned on for in-game text.
- All glyphs are now "twisted": the leading edge is brought a small distance forward, to prevent z-fighting in overlapping (kerned) glyphs. This happens both in the game engine and the rest of the UI, but should have no effect in the UI due to Z-compression in the clipping matrix.
Reviewed and approved by bdiego; see patch [#29882] in the tracker. Tested by dfelinto.