chore: Minor refactoring

May change the shader parsing code to use this code or delete it in
future.

Source/ShaderModel.swift

@@ -53,7 +53,7 @@ extension ShaderConfigSerialization {
  return ShaderModel(passes: passes, textures: textures, parameters: parameters)
  }
 
- fileprivate static func makeShaderPassModel(pass i: Int, from d: [String: String]) throws -> ShaderPassModel {
+ private static func makeShaderPassModel(pass i: Int, from d: [String: String]) throws -> ShaderPassModel {
  let key = "shader\(i)"
  guard let shader = d[key] else {
  throw Errors.missingKey(key)
@@ -87,7 +87,7 @@ extension ShaderConfigSerialization {
  return pass
  }
 
- fileprivate static func makeTextures(from d: [String: String]) -> [ShaderTextureModel] {
+ private static func makeTextures(from d: [String: String]) -> [ShaderTextureModel] {
  guard let tv = d["textures"] else {
  return []
  }
@@ -120,7 +120,7 @@ extension ShaderConfigSerialization {
  return res
  }
 
- fileprivate static func makeParameters(from d: [String: String]) -> [ShaderParameterModel] {
+ private static func makeParameters(from d: [String: String]) -> [ShaderParameterModel] {
  guard let pv = d["parameters"] else {
  return []
  }
@@ -161,10 +161,6 @@ extension ShaderConfigSerialization {
  ]
 }
 
-extension String {
- fileprivate var boolValue: Bool? { Bool(self) }
-}
-
 public class ShaderModel {
  public var passes: [ShaderPassModel]
  public var textures: [ShaderTextureModel]