noise-slur: use gegl-op.h
noise-pick: use gegl-op.h
noise-hurl: use gegl-op.h
noise-hsv: use gegl-.op.h
noise-cie-lch: use gegl-op.h
property-keys: improve value and ui range handling

For both double and int properties if "min" or "max" is set; initialize
corresponding "ui-min" and "ui-max" to its values if they are not set
explicitly. Warn if "ui-min" or "ui-max" is out of range.
noise-reduction: add missing nick
panorama-projection: add missing nick
motion-blur-circular: add missing nick
properties: move seed to last property in many ops
make the label argument mandatory, and not based on key/value

Not having it, leads to untranslated strings in the UI; it means
gegl_property_double (foo, NULL) no longer is sufficient when prototyping an
op.
property meta-data: s/blurb/description

With the nick a mandatory argument; the only odd inherited gobject terminology
is "blurb", using the more descriptive "description" in the property
registration yields API assymetry.. but people manually working with
GParamSpecs should know what they are doing.