rename vercos to coversin

The code to compute 1 - sin(x) belongs to coversin, not vercos.

help/vercos

@@ -1,67 +0,0 @@
-NAME
-    vercos - versed cosine
-
-SYNOPSIS
-    vercos(x [,eps])
-
-TYPES
-    x		number (real or complex)
-    eps		0 < real < 1, defaults to epsilon()
-
-    return	number
-
-DESCRIPTION
-    Calculate the versed cosine of x to a multiple of eps with error less in
-    absolute value than .75 * eps.
-
-    The versed cosine function is sometimes called coversin, sometimes called cvs,
-    may be defined as:
-
-    	vercos(x) = 1 - sin(x)
-
-EXAMPLE
-    ; print vercos(0.2), vercos(3/7), vercos(-31)
-    0.80133066920493878454 0.58442814500694799193 0.59596235467693499395
-
-    ; print vercos(1, 1e-5), vercos(1, 1e-10), vercos(1, 1e-15), vercos(1, 1e-20)
-    0.15853 0.1585290152 0.158529015192104 0.15852901519210349335
-
-    ; print vercos(2 + 3i, 1e-5), vercos(2 + 3i, 1e-10)
-    -8.1545+4.16891i -8.1544991469+4.16890696i
-
-    ; pi = pi(1e-20)
-    ; print vercos(pi/6, 1e-10), vercos(pi/2, 1e-10), vercos(pi, 1e-10), vercos(3*pi/2, 1e-10)
-    0.5 0 1 2
-
-LIMITS
-    0 < eps < 1
-
-LINK LIBRARY
-    NUMBER *qvercos(NUMBER *x, NUMBER *eps)
-    COMPLEX *c_vercos(COMPLEX *x, NUMBER *eps)
-
-SEE ALSO
-    sin, cos, tan, sec, csc, cot, epsilon
-    versin
-
-## Copyright (C) 2023  Landon Curt Noll
-##
-## Calc is open software; you can redistribute it and/or modify it under
-## the terms of the version 2.1 of the GNU Lesser General Public License
-## as published by the Free Software Foundation.
-##
-## Calc is distributed in the hope that it will be useful, but WITHOUT
-## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
-## or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU Lesser General
-## Public License for more details.
-##
-## A copy of version 2.1 of the GNU Lesser General Public License is
-## distributed with calc under the filename COPYING-LGPL.  You should have
-## received a copy with calc; if not, write to Free Software Foundation, Inc.
-## 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
-##
-## Under source code control:	2023/08/31 23:07:08
-## File existed as early as:	2023
-##
-## chongo <was here> /\oo/\	http://www.isthe.com/chongo/
-## Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/