* Add Dart and Rust highlighting * Update German translation * Update SDK, build tools

This is a very simple generic text editor which may be used standalone or to show or edit any sort of text file from another app. If you select a text file in a file manager or similar app you will be offered the option of using this editor along with whatever other apps you have installed that can show or edit a text file. Files will initially be opened read only, long touch on the display or touch the edit item in the toolbar to enable editing. * Regular expression text search * View markdown in browser or html viewer * Optional auto save * Optional word wrap * Optional suggestions * Optional syntax highlighting * Character set detection and selection * Light/Dark/Black/Retro themes * Small/Medium/Large text size * Monospace/Proportional typefaces