ASN1: rewrite _decode_der

this rewrite makes phpseclib better able to handle indef lengths,
which had previously been untested.
ASN1: CS adjustment (rm whitespace at eol)
ASN1: add unit tests for indefinite length decoding
ASN1: cs adjustments to unit test
ASN1: unit test adjustments
ASN1: another unit test update
ASN1: one more unit test change
Merge pull request #462 from terrafrost/asn1-handle-indef-lengths

ASN1: rewrite _decode_der

* terrafrost/asn1-handle-indef-lengths:
  ASN1: one more unit test change
  ASN1: another unit test update
  ASN1: unit test adjustments
  ASN1: cs adjustments to unit test
  ASN1: add unit tests for indefinite length decoding
  ASN1: CS adjustment (rm whitespace at eol)
  ASN1: rewrite _decode_der