Updated the new post button with gradient fill.

Changelog-Changed: Added damus gradient to post button
Closes: #244

damus/Assets.xcassets/Colors/DamusBlue.colorset/Contents.json

@@ -0,0 +1,38 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0xFF",
+          "green" : "0x4D",
+          "red" : "0x4B"
+        }
+      },
+      "idiom" : "universal"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0xFF",
+          "green" : "0x4D",
+          "red" : "0x4B"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

damus/Assets.xcassets/Colors/DamusPurple.colorset/Contents.json

@@ -0,0 +1,38 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0xC5",
+          "green" : "0x43",
+          "red" : "0xCC"
+        }
+      },
+      "idiom" : "universal"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0xC5",
+          "green" : "0x43",
+          "red" : "0xCC"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

damus/Views/PostButton.swift

@@ -8,13 +8,20 @@
 import Foundation
 import SwiftUI
 
+let BUTTON_SIZE = 57.0
+let LINEAR_GRADIENT = LinearGradient(gradient: Gradient(colors: [
+    Color("DamusPurple"),
+    Color("DamusBlue")
+]), startPoint: .topTrailing, endPoint: .bottomTrailing)
+
+
 func PostButton(action: @escaping () -> ()) -> some View {
     return Button(action: action, label: {
         Image(systemName: "plus")
             .font(.system(.title2))
             .foregroundColor(Color.white)
-            .frame(width: 57, height: 57, alignment: .center)
-            .background(Color.accentColor)
+            .frame(width: BUTTON_SIZE, height: BUTTON_SIZE, alignment: .center)
+            .background(LINEAR_GRADIENT)
             .cornerRadius(38.5)
             .padding()
             .shadow(color: Color.black.opacity(0.3),