v0.2.0

Added

• pc_check: :ignore option of Sinetex.open/2: skips the C10 check and picks
  the sender by C13 alone, for counterparties that do not fill C10/C12 with the
  PCs of the certificates. The default (:strict) is unchanged.
• serial: option of Sinetex.Certificate.load/2 and Sinetex.Identity.load/3:
  the number to write in C11/C13, for certificates whose serial number does not
  fit the field or that a counterparty identifies by another number.
• compression_level: option of Sinetex.seal/2. Without it the output is the
  same as before.
• How to read a PKCS#12 file (.pfx, .p12), in the README and the guide.

Changed

• Sinetex.open/2 accepts C07 = 0x00 when the content is not encrypted
  (C04 2, 3, 6 and 10), since there is no symmetric key to select. Other
  invalid values still give 0x04.
• The "empty" header (§5.6.3) is also recognized with the serial number zero
  written as text (32 × "0") in C11 and C13. It still needs
  allow_clear: true.
• inspect/1 of a Sinetex.Error shows the codes in reason as numbers, not
  as a charlist.