Update manual previews

Author: ERSUCC

.gitignore

@@ -30,8 +30,6 @@ target/
 /Code Examples/File Output Example.png
 /Code Examples/Fully Connected Network Example.png
 /Code Examples/Extensions Examples/gis/GIS General Examples.png
-/Code Examples/Extensions Examples/gis/GIS Gradient Example.png
-/Code Examples/Extensions Examples/nw/NW General Examples.png
 /Code Examples/Extensions Examples/palette/Color Bubbles.png
 /Code Examples/Extensions Examples/palette/Color Painting.png
 /Code Examples/Extensions Examples/palette/Color Reveal.png
@@ -211,9 +209,7 @@ target/
 /Sample Models/Art/Diffusion Graphics.png
 /Sample Models/Art/Fireworks.png
 /Sample Models/Art/Follower.png
-/Sample Models/Art/GenJam - Duple.png
 /Sample Models/Art/Optical Illusions.png
-/Sample Models/Art/Sound Machines.png
 /Sample Models/Art/Geometron Top-Down.png
 /Sample Models/Art/Kaleidoscope.png
 /Sample Models/Biology/HIV.png
@@ -242,7 +238,6 @@ target/
 /Sample Models/Biology/Evolution/Genetic Drift/GenDrift P local.png
 /Sample Models/Biology/Evolution/Genetic Drift/GenDrift T interact.png
 /Sample Models/Biology/Evolution/Genetic Drift/GenDrift T reproduce.png
-/Sample Models/Biology/Evolution/Mammoths.png
 /Sample Models/Biology/Evolution/Mimicry.png
 /Sample Models/Biology/Evolution/Peppered Moths.png
 /Sample Models/Biology/Evolution/Sex Ratio Equilibrium.png
@@ -386,7 +381,6 @@ target/
 /Sample Models/Earth Science/River Meanders.png
 /Sample Models/Earth Science/Unverified/Lightning.png
 /Sample Models/Games/Ant Adaptation.png
-/Sample Models/Games/Frogger.png
 /Sample Models/Games/Lunar Lander.png
 /Sample Models/Games/Minesweeper.png
 /Sample Models/Games/Pac-Man.png
@@ -397,6 +391,8 @@ target/
 /Sample Models/Mathematics/3D Solids.png
 /Sample Models/Mathematics/3D Surface.png
 /Sample Models/Mathematics/Color Fractions.png
+/Sample Models/Mathematics/Conic Sections 1.png
+/Sample Models/Mathematics/Conic Sections 2.png
 /Sample Models/Mathematics/Conic Sections/Emergent Shapes - Ellipse.png
 /Sample Models/Mathematics/Conic Sections/Emergent Shapes - Hyperbola.png
 /Sample Models/Mathematics/Conic Sections/Emergent Shapes - Parabola.png