Add extension parameter JFLOAT_TRELLIS_DELTA_DC_WEIGHT that controls
how distortion is calculated in DC trellis quantization. The parameter
defines weighting between actual distortion of DC and distortion of
vertical gradient of DC.
By default the parameter is 0.0 and has no effect.
Addresses #117
This eliminates JBOOLEAN_USE_MOZ_DEFAULTS and replaces it with
JINT_COMPRESS_PROFILE, a more flexible and descriptive parameter. Currently,
this new parameter works in much the same way as the old-- it changes the
behavior of jpeg_set_defaults(). It currently supports only two values
(max. compression, i.e. mozjpeg defaults, and fastest, i.e. libjpeg-turbo
defaults), but it can be extended in the future with additional profiles that
balance compression ratio with performance.
This includes more descriptive text for the project summary (the same
text that is in the package descriptions), a more thorough description of the
libjpeg API extensibility framework, reformatting to improve readability
(particularly on 80-column terminals), and numerous grammar tweaks.
