chore(CHANGELOG): add 4.1.0 changelog

CHANGELOG.md

+# Changelog
+
+## 4.1.0 - 2017-07-19
+
+### Features
+
+- Add tooltips on `recording` and `screenshot` buttons in `Calls Window`.
+- Show notifications on `recording` and `screenshot`.
+- Show `XXX is typing...` in `Timeline` and `Chat View`.
+- Handle correctly `SIGINT`.
+- Handle clicks on SIP URI in chat messages.
+- Show video framerate in `Calls Stats`.
+- Add a `Logs` menu entry in `Settings Window`, it provides send, remove, activate buttons...
+- Supports EXIF orientation for file transfer images preview.
+- Echo canceller supports 48kHz.
+
+### Fixes
+
+- Handle correctly ringer device changes in `Settings Window`.
+- In `Video Settings`, display FPS field only in `custom preset` mode.
+- Use now the directory containing user documents files for saved video/audio/screenshots.
+- Update `Chat View` correctly if it is used in many windows.
+- Update correctly selected language when app is restarted.
+- Avoid a deadlock on Mac OS when a call ends in fullscreen mode.
+- Application can be started from one binary only.
+- Single instance is now supported with flatpak. (It uses D-Bus.)