Added Plugin support (#102)

* Build refactoring and initial plugin support

* Possibly fixed linux / mac build

* Added libdl to libglad build script

* Add glfw to imgui dependencies

* Refactored common functionality into "libimhex" for plugins

* Added plugin loading and example plugin

* Added proper API for creating a custom view and a custom tools entry with plugins

plugins/libimhex/source/views/view.cpp

@@ -0,0 +1,107 @@
+#include "views/view.hpp"
+
+#include "imgui.h"
+
+#include <functional>
+#include <string>
+#include <vector>
+
+namespace hex {
+
+
+    View::View(std::string viewName) : m_viewName(viewName) { }
+
+    void View::drawMenu() { }
+    bool View::handleShortcut(int key, int mods) { return false; }
+
+    std::vector<std::function<void()>>& View::getDeferedCalls() {
+        return View::s_deferedCalls;
+    }
+
+    void View::postEvent(Events eventType, const void *userData) {
+        View::s_eventManager.post(eventType, userData);
+    }
+
+    void View::drawCommonInterfaces() {
+        if (ImGui::BeginPopupModal("Error", nullptr, ImGuiWindowFlags_NoResize)) {
+            ImGui::NewLine();
+            if (ImGui::BeginChild("##scrolling", ImVec2(300, 100))) {
+                ImGui::SetCursorPosX((300 - ImGui::CalcTextSize(View::s_errorMessage.c_str(), nullptr, false).x) / 2.0F);
+                ImGui::TextWrapped("%s", View::s_errorMessage.c_str());
+                ImGui::EndChild();
+            }
+            ImGui::NewLine();
+            ImGui::SetCursorPosX(75);
+            if (ImGui::Button("Okay", ImVec2(150, 20)))
+                ImGui::CloseCurrentPopup();
+            ImGui::EndPopup();
+        }
+    }
+
+    void View::showErrorPopup(std::string_view errorMessage) {
+        View::s_errorMessage = errorMessage;
+
+        ImGui::OpenPopup("Error");
+    }
+
+    void View::setWindowPosition(s32 x, s32 y) {
+        View::s_windowPos = ImVec2(x, y);
+    }
+
+    const ImVec2& View::getWindowPosition() {
+        return View::s_windowPos;
+    }
+
+    void View::setWindowSize(s32 width, s32 height) {
+        View::s_windowSize = ImVec2(width, height);
+    }
+
+    const ImVec2& View::getWindowSize() {
+        return View::s_windowSize;
+    }
+
+    bool View::hasViewMenuItemEntry() {
+        return true;
+    }
+
+    ImVec2 View::getMinSize() {
+        return ImVec2(480, 720);
+    }
+
+    ImVec2 View::getMaxSize() {
+        return ImVec2(FLT_MAX, FLT_MAX);
+    }
+
+
+    bool& View::getWindowOpenState() {
+        return this->m_windowOpen;
+    }
+
+    const std::string View::getName() const {
+        return this->m_viewName;
+    }
+
+    void View::subscribeEvent(Events eventType, std::function<void(const void*)> callback) {
+        View::s_eventManager.subscribe(eventType, this, callback);
+    }
+
+    void View::unsubscribeEvent(Events eventType) {
+        View::s_eventManager.unsubscribe(eventType, this);
+    }
+
+    void View::doLater(std::function<void()> &&function) {
+        View::s_deferedCalls.push_back(function);
+    }
+
+    void View::confirmButtons(const char *textLeft, const char *textRight, std::function<void()> leftButtonFn, std::function<void()> rightButtonFn) {
+        auto width = ImGui::GetWindowWidth();
+        ImGui::SetCursorPosX(width / 9);
+        if (ImGui::Button(textLeft, ImVec2(width / 3, 0)))
+            leftButtonFn();
+        ImGui::SameLine();
+        ImGui::SetCursorPosX(width / 9 * 5);
+        if (ImGui::Button(textRight, ImVec2(width / 3, 0)))
+            rightButtonFn();
+    }
+
+}