Capture ImGui in screenshots#7236

MjnMixael wants to merge 1 commit intoscp-fs2open:masterscp-fs2open/fs2open.github.com:masterfrom

MjnMixael:fix_imgui_lab_screenshotsMjnMixael/fs2open.github.com:fix_imgui_lab_screenshotsCopy head branch name to clipboard