MAINT: avoid an overflow in rice pdf
MAINT: change von Mises support to [-pi, pi]
Revert "MAINT: change von Mises support to [-pi, pi]"

This reverts commit 024ce0b65b1e1c6c06a2345e13d317cbd5757b1f.
DOC: add a note to the vonmises docstring

Document the fact that von Mises distribution is not designed
to work as a fully-fledged distribution on a segment of a real line.
ENH: define a vonmises_line as proper distribution on [-pi, pi]

(yes, this undoes the previous commit, as discussed in the PR)
BUG: fix moments for invgamma

n-th moment only exists for n < a.
TST: mark the ncf normalization test as a knownfail
MAINT: use explicit formulas for invgamma stats
MAINT: return nan instead inf for skew/kurtosis
MAINT: avoid spurious warnings for invalid arguments
TST: [stats] add tests for the moments

Mark known fails as such.
BUG: stop liming the support for betaprime distribution.

Cutting off the support at a large value does not seem necessary.
All tests pass, no new problems seem to show up.
MAINT: deduplicate some tests (discrete vs continuous distributions)

Move tests common to discrete and continuous distributions to a new
common_tests.py, and import from there.
BUG: optimize: ensure line search is not confused by float issues

Detect non-finite (nan, inf) results from _cubicmin and _quadmin so that
the rest of the line search doesn't become confused.  Avoids problems
when float overflows etc. occur.

Also replace intermediate value checks by exceptions.
MAINT: address comments
MAINT: typos, fixed
Merge pull request #2845 from EvgeniBurovski/rice_pdf

improve numerical stability of the Rice distribution
MAINT: remove rice._logpdf(), is the same as rv_continuous._logpdf().
Merge pull request #2849 from EvgeniBurovski/invgamma

fix moments for invgamma
Merge pull request #2864 from pv/linesearch-nan

BUG: optimize: ensure line search is not confused by float issues