fixed custom ABC string not being displayed
simplified the Arabic numbers code
simplified displaying the Arabic question mark on the virtual keyboard
Arabic numbers are properly displayed on the virtual keyboard
injected word frequencies and sorted the dictionary
updated the readme
* moved the source languages out of assets/ into their own directory (#356)
* split build.gradle into several smaller files
* improved word frequency validation during build time
* slightly optimized dictionary loading speed using pre-calculated file size
* fixed a potential crash when loading invalid assets
* fixed dictionary loading progress starting at 100% then jumping to 0% when manually loading two dictionaries one after another
* documentation update