pgsql: Add trigonometric functions that work in degrees.

Add trigonometric functions that work in degrees.

The implementations go to some lengths to deliver exact results for values
where an exact result can be expected, such as sind(30) = 0.5 exactly.

Dean Rasheed, reviewed by Michael Paquier

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/e1bd684a34c11139a1bf4e5200c3bbe59a0fbfad

Modified Files
--------------
doc/src/sgml/func.sgml | 72 +++-
src/backend/utils/adt/float.c | 437 +++++++++++++++++++-
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.h | 18 +
src/include/utils/builtins.h | 8 +
.../expected/float8-exp-three-digits-win32.out | 77 ++++
src/test/regress/expected/float8-small-is-zero.out | 77 ++++
.../regress/expected/float8-small-is-zero_1.out | 77 ++++
src/test/regress/expected/float8.out | 77 ++++
src/test/regress/sql/float8.sql | 24 ++
10 files changed, 860 insertions(+), 9 deletions(-)