* Fixed and added tests for `quantile' and `median', documented them
* Added `sort-samples', documented it
* Removed `real-quantile' and `real-median' (too many design choices
right now; will revisit when implementing Kernel Density Estimators)
* Documented `absdev' and `absdev/median'
* Fixed `update-statistics*': now uses O(1) space as advertised (if the
sequences of values and weights both use O(1) space)
* Changed types of binning functions: allows using #:key in the future
(when TR supports function type cases that differ only by keyword
argument types better), places optional weights at the end like other
statistics functions
* Clarified binning docs about sort stability and half-open intervals
Cleaned up expected value code a little
Refactored running statistics objects (hid private fields, added
`update-statistics*')
Documented expected value functions and running statistics
Removed `bfpsi0' from bigfloat tests (DrDr's libmpfr doesn't have it)
Commented out custodian shutdown callback that frees MPFR's cache
(something's broken)
Cleaned up other docs in preparation for alpha-testing announcement
Created `math/utils' module for stuff that doesn't go anywhere else (e.g.
FFT scaling convention, max-math-threads parameters)
Reduced the number of macros that expand to applications of `array-map'
Added `flvector-sum', defined `flsum' in terms of it
Reduced the number of pointwise `flvector', `flarray' and `fcarray' operations
Reworked `inline-build-flvector' and `inline-flvector-map' to be faster and
expand to less code in both typed and untyped Racket
Redefined conversions like `list->flvector' in terms of for loops (can do
it now that TR has working `for/flvector:', etc.)
clean up build
Moved `float-complex?' and `number->float-complex' to `math/base',
documented them
Documented `flexpt1p'
Removed `samples->immutable-hash' (not covariant anyway; not going to
use hashes)
