v1.19

• Tightening default style a little.
• Added ImGuiStyleVar_WindowRounding enum for PushStyleVar() API.
• Added SliderInt2(), SliderInt3(), SliderInt4() for consistency.
• Widgets more consistently handle empty labels (starting with ## mark) for their size calculation.
• Fixed crashing with zero sized frame-buffer.
• Fixed ImGui::Combo() not registering its size properly when clipped out of screen.
• Renamed second parameter to Begin() to 'bool* p_opened' to be a little more self-explanatory. Added more comments on the use of Begin().
• Logging: Added LogText() to pass text straight to the log output (tty/clipboard/file) without rendering it.
• Logging: Added LogFinish() to stop logging at an arbitrary point.
• Logging: Log depth padding relative to start depth.
• Logging: Tree nodes and headers looking better when logged to text.
• Logging: Log outputs \r\n under Windows to play it nicely with \n unaware tools such as Notepad.
• Style editor: added a button to output colors to clipboard/tty.
• OpenGL3 example: fix growing of VBO.
• Cleanup and other minor fixes.