Implement customizable underline unselected color, margins for underline, height for underline and new segmentFitsScreen option

.gitignore

@@ -2,3 +2,4 @@ ScrollableSegmentedControl.xcodeproj/project.xcworkspace/xcuserdata
 ScrollableSegmentedControl.xcodeproj/xcuserdata
 Demo/ScrollableSegmentedControlDemo/ScrollableSegmentedControlDemo.xcodeproj/project.xcworkspace/xcuserdata
 Demo/ScrollableSegmentedControlDemo/ScrollableSegmentedControlDemo.xcodeproj/xcuserdata
+.swiftpm

Demo/ScrollableSegmentedControlDemo/ScrollableSegmentedControlDemo.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

Package.swift

@@ -0,0 +1,24 @@
+// swift-tools-version:5.5
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "ScrollableSegmentedControl",
+    products: [
+        // Products define the executables and libraries a package produces, and make them visible to other packages.
+        .library(
+            name: "ScrollableSegmentedControl",
+            targets: ["ScrollableSegmentedControl"]),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages this package depends on.
+        .target(
+            name: "ScrollableSegmentedControl",
+            dependencies: []),
+        .testTarget(
+            name: "ScrollableSegmentedControlTests",
+            dependencies: ["ScrollableSegmentedControl"]),
+    ]
+)