Minor cleanups

[mlocati]

• Use new static instead of new self in IPv4::shift() and IPv6::shift(), for consistency with the rest of the classes
• Pass the $flags to IPv6::parseString() in Pattern::parseString(), as already done for IPv4
• Fix typos in docblocks of BinaryMath and NumberInChunks
• Fix typos in the range type names ("Indentify", "Linked-scoped")
• Document that Subnet::$rangeType may be false (as in Pattern)
• Simplify Single::getNetworkPrefix()
• README:
  • fix wrong examples
  • the start address of a subnet is normalized, so 0:0::1/64 is rendered as ::/64)
  • fix typos
  • use echo instead of var_export for string outputs
  • document:
    • toOctal()
    • toHexadecimal()
    • toMixedIPv6IPv4String()
    • getBytes()
    • getWords()
    • getBits()
    • fromBytes()
    • fromWords()
    • getNetworkPrefix()
    • getReservedRanges()
    • T_CGNAT
    • the range type of 6to4/IPv4-mapped addresses and ranges
    • the limits of pattern ranges

[coveralls]

coverage: 98.701% (-0.001%) from 98.702% — mlocati-forks:cleanup-minor-fixes into mlocati:main