Blender Git Loki

Timeline: Draw keyframe lines at 60% height

This patch updates the timeline editor. Ordinarily, it draws the
yellow keyframe lines at 100% of the available height. This becomes an
issue when there are keyframes for every frame, which can happen when
importing motion capture data or recording animations from the BGE. In
such cases, the green "current frame" indicator becomes very hard to
see.

This patch restricts the drawing to the bottom 60% of the available
space, thereby making the "current frame" indicator more visible.

Reviewers: aligorith

Reviewed By: aligorith

Subscribers: Severin

Projects: #bf_blender

Differential Revision: https://developer.blender.org/D1033