Changes for release v3.0

[mike42]

Breaking changes for developers who are upgrading.

• Support for PHP 5.x and HHVM has been removed. PHP 7.0 or higher is required from this version.
• The intl PHP extension is now required (see docs). This replaces the use of mbstring and iconv, which are no longer used.
• composer is now required to correctly load dependencies, where it was previously optional.
• Printer::text() will now throw an Exception if invalid UTF-8 is supplied. Use Printer::textRaw() if you are encoding text manually.
• Printer-specific sub-classes of CapabilityProfile have been removed (eg. StarCapabilityProfile). Use a named profile with CapabilityProfile::load() instead.
• The API now uses scalar and return type hinting in some places, which makes it more strict than it was previously.

New features:

• Inclusion of new printer profiles from escpos-printer-db.
• gfx-php has been added as a dependency, which allows image processing to work without gd or imagick being present in most cases.
• A new MultiplePrintConnector has been added, which allows developers to route identical print data to multiple printers simultaneously.

Experimental features:

• A new UnifontPrintBuffer, which uses glyphs from a GNU Unifont hex file as an alternative to the on-board printer fonts. See the included unifont-print-buffer.php example for usage.

Bug fixes:

• Added checks where temporary files are created, to give clearer error messages on setups where the temp directory is misconfigured, see Filename cannot be empty issue in print from mac machine #362