Improvements to the README

README.markdown

@@ -1,4 +1,4 @@
-_Q: Yet another RepRap slicer?_
+_Q: Oh cool, a new RepRap slicer?_
 
 A: Yes.
 
@@ -6,10 +6,10 @@ A: Yes.
 
 ## What's it?
 
-Slic3r is (er, will be) an STL-to-GCODE translator for RepRap 3D printers, 
+Slic3r is an STL-to-GCODE translator for RepRap 3D printers, 
 like Enrique's Skeinforge or RevK's E3D.
 
-## Why another one? Why Perl?
+## Why a new one? Why Perl?
 
 The purpose is to build something more maintainable and flexible than both
 Skeinforge and E3D. The code makes extensive use of object-oriented 
@@ -47,18 +47,81 @@ Roadmap includes the following goals:
 * support material for internal perimeters;
 * ability to infill in the direction of bridges;
 * cool;
+* other fill patterns;
 * nice packaging for cross-platform deployment.
 
 ## Is it usable already?
 
-Yes. I need to write a script to install dependencies.
+Yes, although its extrusion math needs to be tested.
+I need to write a script to install dependencies and to package
+dependency-free executables for main platforms.
 
 ## Can I help?
 
 Sure! Send patches and/or drop me a line at aar@cpan.org. You can also 
-find me in #RepRap on FreeNode with the nickname _Sound_.
+find me in #reprap on FreeNode with the nickname _Sound_.
 
 ## What's Slic3r license?
 
 Slic3r is dual-licensed under the _Perl Artistic License_ and the _AGPLv3_.
-The author is Alessandro Ranellucci (that's me).
+The author is Alessandro Ranellucci (me).
+
+## How can I invoke slic3r.pl?
+
+    Usage: slic3r.pl [ OPTIONS ] file.stl
+    
+        --help              Output this usage screen and exit
+        
+      Printer options:
+        --nozzle-diameter   Diameter of nozzle in mm (default: 0.45)
+        --print-center      Coordinates of the point to center the print around 
+                            (default: 100,100)
+        --use-relative-e-distances
+                            Use relative distances for extrusion in GCODE output
+        --z-offset          Additional height in mm to add to vertical coordinates
+                            (+/-, default: 0)
+        
+      Filament options:
+        --filament-diameter Diameter of your raw filament (default: 3)
+        --filament-packing-density
+                            Ratio of the extruded volume over volume pushed 
+                            into the extruder (default: 0.85)
+        
+      Speed options:
+        --print-feed-rate   Speed of print moves in mm/sec (default: 60)
+        --travel-feed-rate  Speed of non-print moves in mm/sec (default: 130)
+        --bottom-layer-speed-ratio
+                            Factor to increase/decrease speeds on bottom 
+                            layer by (default: 0.6)
+        
+      Accuracy options:
+        --layer-height      Layer height in mm (default: 0.4)
+      
+      Print options:
+        --perimeters        Number of perimeters/horizontal skins (range: 1+, 
+                            default: 3)
+        --solid-layers      Number of solid layers to do for top/bottom surfaces
+                            (range: 1+, default: 3)
+        --fill-density      Infill density (range: 0-1, default: 0.4)
+        --fill-angle        Infill angle in degrees (range: 0-90, default: 0)
+        --temperature       Extrusion temperature (default: 195)
+      
+      Retraction options:
+        --retract-length    Length of retraction in mm when pausing extrusion 
+                            (default: 2)
+        --retract-speed     Speed for retraction in mm/sec (default: 40)
+        --retract-restart-extra
+                            Additional amount of filament in mm to push after
+                            compensating retraction (default: 0)
+       Skirt options:
+        --skirts            Number of skirts to draw (default: 1)
+        --skirt-distance    Distance in mm between innermost skirt and object 
+                            (default: 6)
+        -o, --output        File to output gcode to (default: <inputfile>.gcode)
+       
+       Transform options:
+        --scale             Factor for scaling input object (default: 1)
+        --rotate            Rotation angle in degrees (0-360, default: 0)
+        --multiply-x        Number of items along X axis (1+, default: 1)
+        --multiply-y        Number of items along Y axis (1+, default: 1)
+        --multiply-distance Distance in mm between copies (default: 6)