Separate multi-words filenames by '_'

Rename foobar.ext to foo_bar.ext.

<https://github.com/Genymobile/scrcpy/pull/226#discussion_r209454865>

app/src/input_manager.h

@@ -0,0 +1,27 @@
+#ifndef INPUTMANAGER_H
+#define INPUTMANAGER_H
+
+#include "common.h"
+#include "controller.h"
+#include "fps_counter.h"
+#include "frames.h"
+#include "screen.h"
+
+struct input_manager {
+    struct controller *controller;
+    struct frames *frames;
+    struct screen *screen;
+};
+
+void input_manager_process_text_input(struct input_manager *input_manager,
+                                      const SDL_TextInputEvent *event);
+void input_manager_process_key(struct input_manager *input_manager,
+                               const SDL_KeyboardEvent *event);
+void input_manager_process_mouse_motion(struct input_manager *input_manager,
+                                        const SDL_MouseMotionEvent *event);
+void input_manager_process_mouse_button(struct input_manager *input_manager,
+                                        const SDL_MouseButtonEvent *event);
+void input_manager_process_mouse_wheel(struct input_manager *input_manager,
+                                       const SDL_MouseWheelEvent *event);
+
+#endif