Version 2.6.0

bugfixes, quickreader & welcome readthedocs/mkdocs

• Create QuickReader, utility for easy navigate and extract information from a CFDI
• Fix Rfc to don't throw an exception if checksum fails, SAT is not following its own standard
• Add Rfc::checkSum() and Rfc::checkSumMatch() to know if the Rfc is following the checksum
• Fix tests that expect Rfc checksum failure
• Fix tests comments on testDescuentoNotSetIfAllConceptosDoesNotHaveDescuento
• Fix CfdiUtils\Elements\Cfdi33\Comprobante::getCfdiRelacionados to don't receive a parameter.
  • For backwards compatibility when it receive a parameter do the same thing but trigger a E_USER_NOTICE
  • Create an special test case ComprobanteGetCfdiRelacionadosTest that catched the E_USER_NOTICE error
• Add CfdiUtils\Elements\Cfdi33\Comprobante::addCfdiRelacionados(array $attributes)
• Add CfdiUtils\Elements\Cfdi33\Comprobante::multiCfdiRelacionado(array $attributes)
• Add tests to assert that Comprobante/Impuestos/(Traslados/Traslado|Retenciones/Retencion)@Impuesto is rounded
• Minor fix at docblocks for packed arguments
• Change all documentation to move from GitHub Wiki to ReadTheDocs https://cfdiutils.readthedocs.io/
  • More documentation pages & a lot of fixes
  • Add .markdownlint.json to run with markdownlint-cli (node), add to travis build process
  • Add mkdocs.yml to run with mkdocs (python), add to travis build process
  • Fix markdown files according to markdownlint
  • Add composer docs and append to general composer build