Support in-memory encoding/decoding

[mthrok]

Add support for file-like object in I/O operations (info/load/save/sox_effects).

• Support file-like object in load function #1158 load
• Support file-like object in info #1108 info
• Support file-like object in apply_effects_file #1166 sox_effect
• Support file-like object in save func #1141 save func
• Add smoke test for sox_io fileobj #1165 smoke test
• Fix fileobj I/O un-deterministic behavior #1297 Fix segfault by calling ftell in place of tell_off #1217 Fix mixed signed/un-signed types in comparison #1236 bug fix
• (Optionally) Change argument name from filepath to src.