* Code base compatible with both Python 2 and Python 3:
    - Supports Python 2.7;
    - Supports Python 3 (through 3.6 to 3.8);
* Added Bematech MP-2800 TH printer model;
* Added support for USB connections;
* Changed base class escpos.impl.epson.GenericESCPOS:
    - Added set_code_page() method;
    - Added set_font() method;
    - Added set_mode() method;
    - Added set_double_strike() method;
    - Changed cut() method behavior to feed page to actual cutter
      position before cut, preventing misplaced paper cut;
* Using standard logging for hex dump on write to device;
* Dependencies are not pinned anymore (soft dependencies);