Update README with solid model manipulation stuff

Also, break-up the description of the 3D rendering into a sub-list as it's become unwieldy.

README.md

@@ -7,32 +7,41 @@ with trails moving outwards from the centre of the screen.](docs/header.jpg)
 system for describing 2D and 3D visuals. [The language](/docs/language.md) is
 designed to encourage an iterative, explorative, play-based approach to
 constructing generative visuals. The engine that runs **Flitter** programs is
-able to live reload all code and assets while retaining current system state
-(thus supporting live-coding) while also having strong support for interacting
-with running programs via MIDI surfaces.
+able to live reload all code (including shaders) and assets (images, models,
+etc.) while retaining current system state - thus supporting live-coding. It
+also has support for interacting with running programs via MIDI surfaces.
 
 **Flitter** is designed for expressivity and ease of engine development over
 raw performance, but is sufficiently fast to be able to do interesting things.
 
 The engine that runs the language is capable of:
 
 - 2D drawing (loosely based on an HTML canvas/SVG model)
-- 3D rendering of primitive shapes and external triangular mesh models (in a
-variety of formats including OBJ and STL); ambient, directional, point and
-spot- light sources with (currently shadowless) [PBR](https://en.wikipedia.org/wiki/Physically_based_rendering)
-material shading; simple fog; perspective and orthographic projections;
-texture-mapping - including with the output of other visual units (like a
-drawing canvas or a video)
-- simulating simple [physical particle systems](/docs/physics.md) (including
+- 3D rendering, including:
+  - primitive box, sphere, cylinder and cone shapes
+  - external triangular mesh models in a variety of formats including OBJ
+    and STL
+  - texture mapping, including with the output of other visual units (e.g., a
+    drawing canvas or a video)
+  - planar slicing and union, difference and intersection of solid models
+  - ambient, directional, point and spotlight sources (currently shadowless)
+  - [PBR](https://en.wikipedia.org/wiki/Physically_based_rendering) material
+    shading, emissive objects and transparency
+  - multiple cameras with individual control over location, field-of-view, near
+    and far clip planes, render buffer size, color depth, MSAA samples,
+    perspective/orthographic projection, fog, conversion to monochrome and
+    colour tinting
+- simulating simple [physical particle systems](/docs/physics.md), including
 spring/rod/rubber-band constraints, gravity, electrostatic charge, inertia,
-drag, barriers and particle collisions)
-- playing videos at arbitrary speeds (including in reverse, although video will
+drag, barriers and particle collisions
+- playing videos at arbitrary speeds, including in reverse (although video will
 stutter if it makes extensive use of P-frames)
-- running GLSL shaders as stacked image generators and filters, with live
-manipulation of uniforms and live reload of source
+- running GLSL shaders as stacked image filters and generators, with per-frame
+control of arbitrary uniforms
 - compositing all of the above and rendering to one or more windows
-- saving rendering output to image and video files (including the lockstep
-frame-by-frame video output suitable for producing perfect loops)
+- saving rendered output to image and video files (including lockstep
+frame-by-frame video output suitable for producing perfect loops and direct
+generation of animated GIFs)
 - driving arbitrary DMX fixtures via a USB DMX interface (currently via an
 Entec-compatible interface or my own crazy hand-built devices)
 - driving a LaserCube plugged in over USB (other lasers probably easy-ish to