Improve builtin function strings, as printed by help builtin,
that use an optional accuracy (epsilon) arg by adding a comma.
Added the following new trigonometric functions:
crd(x [,eps]) trigonometric chord of a unit circle
acrd(x [,eps]) inverse trigonometric chord of a unit circle
Added the following new trigonometric functions:
exsec(x [,eps]) exterior trigonometric secant
aexsec(x [,eps]) inverse exterior trigonometric secant
excsc(x [,eps]) exterior trigonometric cosecant
aexcsc(x [,eps]) inverse exterior trigonometric cosecant
Added to test 95dd and test9500.trigeq.cal to the calc regression test
suite to perform extensive test of trigonometric functions.
Added to test 34dd, some if the missing inverse trigonometric tests.
