themes.xml: Improve control visibility in dark theme
values-zh/strings.xml: Update Chinese (Simplified) translation
.gitignore: OCD fixes :)
values-zh/strings.xml: "Above", not "At the top of"
values-zh/strings.xml: "Open" -> "Close", "Drawer navigation" -> "Navigation drawer"
Merge pull request #178 from zhaofengli/master

UI tweak + Chinese translation update