[CM] Snd 22.9

[bil at ccrma.Stanford.EDU]

Snd 22.9

s7: added support for NaN "payloads": new functions nan and nan-payload
       to create such a NaN or get its payload, read-time support for
       +nan.123 (123 is the payload), and so on.
     S7_EXPORT for MSVC thanks to vladimir florentino

checked: sbcl 2.2.10

Thanks!:  Hyogeol Lee, vladimir florentino