replaced clojure-based turtle language interpreter with JScheme 7.2 interpreter;
set up filtering of unused classes using both custom lein-droid build tasks and proguard;
added stringification for InterruptedException;
made error output scrollable;
renamed error output tab to mention other output except errors;
reworked jscheme.init;
added general output stream linked to TextView in errors tab;
directed jscheme to output errors to new output stream;
used new extract-stacktrace utility function;
moved jscheme into separate directory
adjusted program editor's source editor height to match content and removed hard limit on the number of lines displayed simultaneously
fixed crash problem when "center yourself" or "refresh" menu option is selected while drawing surface was not initialized
temporary commit
added handling of absent AndExplorer;
did some minor cleanup;
cleared project.clj;
added local jars of dependencies;
bumped versions of turtle-geometry and lein-droid;
added license and readme for github