fixed a bug with incorrect handling of the BACK button/gesture

* new shortcuts: CTRL+Z - undo; CTRL+X/C/V - cut/copy/paste; CTRL+O - load; CTRL+S - save; CTRL+N - new song;
* new shortcuts: SHIFT+F3 - previous sound (silent); SHIFT+F4 - next sound (silent);
* additional visualization modes: Menu -> App Settings -> Visualizer;
* bug fixes.

* iOS 11 support has been dropped; now the minimum is 12;
* now you can load sound files in the following formats: WAV (PCM, uncompressed), AIFF (PCM, uncompressed), OGG (Vorbis), MP3, FLAC;
* auto-repeat in the virtual (on-screen) text keyboard;
* bug fixes.

* iOS 9 support has been dropped; now the minimum is 11;
* now you can use the PC keyboard to play notes: ZSXDCVGBHNM... - current octave; Q2W3ER5T6Y7U... - current octave + 1;
* shortcuts: F1 or '-' - octave down; F2 or '+' - octave up; F3 - previous sound; F4 - next sound; SPACE - play/stop; SHIFT+SPACE - play pattern/stop;
* bug fixes.

bug fixes

* new song - Example06;
* bug fixes.

* user files are now available through the Files app;
* lists of recent files and folders have been added to the file browser;
* bug fixes.

bug fixes.

* export to XM (eXtended Module of the FastTracker2) - this file can be loaded by any modern music tracker/player (for example, SunVox);
* sound editor: "reduce size / 2 (lossy)" function has been added;
* bugs fixed.

Changed icons and screenshots

* new song parameter - Shuffle;
* now any song parameters (BPM, Shuffle, Number of lines, Number of tracks) can be changed in the Main Menu -> Song Settings;
* Audiobus 2 and IAA (partially) support;
* bugs fixed.

* additional Document Browser functions: Remove, Rename, Cut, Copy, Paste, Create Directory;
* now you can see the document size in the Browser;
* bugs fixed.

* updated Audiobus library;
* fixed bug with iOS7 support.

Bugs fixed

* Audiobus and JACK support;
* additional audio/gfx settings in the Main Menu -> Preferences -> Audio & Graphics;
* additional background images (Main Menu -> Preferences -> Background);
* now you can play any loaded WAV sound with its original speed on the first note of the 6th octave;
* bugs fixed.