Fix clip before tape write

[catfact]

added hardclipper in tape writer class.

out-of-range values were wrapping when encoded to fixed point. (seems like pretty bad behavior from libsndfile, but w/e.)

could probably implement the hardclipper more efficiently, without conditionals, but this will get it done.

[simonvanderveldt]

@catfact libsndfile/libsndfile#294 (comment)

[catfact]

@simonvanderveldt thanks! takeaway is to set SFC_SET_CLIPPING. so, will do that and report back.

[catfact]

thanks using SF_SET_CLIPPING instead, which is surely more efficient and definitely happens on the right thread.

NB: have only tested on x64 so far

[tehn]

fixes #888

(will test on hardware today)