A3DGE Code

* Replaced the Log object with the (Do)Log method in the TA3DGEApplication
class. This simplifies a lot the thing.
* TModelLoader type moved to unit a3dge.Model3D (forgotten).
+ Added property Windowed to TDisplay. It is also affected by configuration and
command-line options, as well as by the DEBUG definition conditional.
* Some documentation fixes, improvements and completions.

* A few improvements in the heightmap rendering.
* ex_world renamed as ex_heightmap.
* Added more movement to ex_heightmap.
* Allegro's directory moved outside the engine directory.
- Removed iff4pas as it isn't used now.
* Added documentation about some methods and properties that weren't fully
explained.

+ Added ambient light.
* Fixed default camera light location.
* Fixed name of unit a3dge.Heightmap.
* Improved the heightmap system. It also uses a bitmap instead of a propietary
file format.
* Fixed application Run by ensuring the gamestate is initialized.
* Fixed PLG colours. Still not perfect though.
* Fixed Wavefront .obj file loader issue when file doesn't define face normals.
* Fixed skybox texture loading that generated rendering glitches due to the use
of rendering filters and mip-maps.
+ ex_world loads and renders a heightmap now. Also added mouse speed, fog,
light and some movement.
+ Added light to objview.

+ Added mouse input.
* Fixed decimal separator issue (see TA3DGEApplication.Initialize).
* Fixed and refactored TSkybox.
+ ex_world uses mouse and skybox now.
+ Added mouse control to objvew.
* Fixed Lazarus project files not using Delphi dialect. Also a few paths.

+ Added property Enabled to TEntity3D.
* Octre improved: constructor uses default values and added a method to change
octree properties.
* several refactorization on TWorld3D making it more coherent and more easy to
use and maintain, modifying behaviors and adding some methods and properties.
- Added a new example to test the TWorld3D class.
* Small fixes in a3dge.PLG and a3dge.Skybox.
* A small improvement in objviewer tool.
- Removed several "inline" stuff.

* Huge improvement of unti a3dge.Math3d: re-ordering, re-naming, and adding
stuff. Note that most is the same.
+ Added pasdoc-hierarchy.txt file to resources.
* A few changes in a3dge.material trying to make in more clean.

+ Added a `TBillboard` model. Should work on z-ordering.

- Removed the documentation CSS file. Silly decission. 8^P
* Completed the TMesh3D class, changing some names by more descriptive ones.
- Removed the old TTexturedModel3D and such because I've...
+ ...added a TTexturedPolyhedron3D, much simpler.
* CreateCube moved to the new unit a3dge.Prims3D.

Restoring docs css.

* TListVector3D renamed as TVector3DList.
+ Added class TMesh3D as base for 3D models.
* TPolyhedron3D refactored to use TMesh3D.
* TPolyhedron3D.Render improved by using better loops, params and less
indirections. Should be slightly faster.