Total engine refactoring (#44)

* totally refactored the Languages, the Database and the IME module. New and more clear folder/package structure

* CharMap and LangHelper are no more

* removed many unused icons, translations and other resources

* deleted the old keymap samples

* Update user-manual.md

* Preferences are stored in Preferences, not in the database.

* removed some unclear and unused settings from the Preferences screen and the code.

* fixed issues with displaying the UI

* removed all non-English words and words with foreign spelling from the English dictionary

* 0 now works as it should in all modes.

* a more clear newline character in suggestions view

* last used input mode is now preserved and restored the next time

* removed the smiley and symbol dialogs

* capsMode -> textCase

* language names are no longer translated

* updated build instructions

* better use of threads for DB operations

* current text candidate is as long as the sequence, to make it more intuitive

* single characters are added to the end of the suggestion, when there are no more in the database

* Added ѝ to Bulgarian character map

* disabled adding words in a user-friendly manner

* when adding a new word is not possible, a toast message appears, for better user experience

* an error is logged when there are duplicate language IDs

* settings -> settings_legacy

* custom Logger class for easier debugging and no logcat flood in the Release version

* removed unnecessary single letters and invalid words from the dictionaries

* more translations cleanup; also corrected some weird translations

* upgraded gradle

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4-all.zip