update major trigonometric help files and regression tests

Improved help files for sin, cos, tan, cot, sec, csc.  In case
of tan, cot, sec, csc corrected help file was corrected to
indicate that complex arguments are allowed.  This was a help
file oversight from long ago when those trigonometric functions

Expanded the calc regression test suite test 34dd to test various
real and complex values for sin, cos, tan, cot, sec, csc.

help/tan

@@ -5,7 +5,7 @@ SYNOPSIS
     tan(x [,eps])
 
 TYPES
-    x		real
+    x		number (real or complex)
     eps		0 < real < 1, defaults to epsilon()
 
     return	real
@@ -18,13 +18,21 @@ EXAMPLE
     ; print tan(1, 1e-5), tan(1, 1e-10), tan(1, 1e-15), tan(1, 1e-20)
     1.55741 1.5574077247 1.557407724654902 1.55740772465490223051
 
+    ; print tan(2 + 3i, 1e-5), tan(2 + 3i, 1e-10)
+    ~-0.00376408798745471014+~1.00323845857938817252i ~-0.00376402563894634508+~1.00323862734859967572i
+
+    ; pi = pi(1e-20)
+    ; print tan(0, 1e-10), tan(pi/6, 1e-10), tan(pi/3, 1e-10), tan(pi, 1e-10)
+    0 0.5773502692 1.7320508076 0
+
+    ; print tan(1/2), tan(5/7), tan(42/7)
+    0.54630248984379051326 0.8670082185107029875 -0.29100619138474915705
+
 LIMITS
-    unlike sin and cos, x must be real
     0 < eps < 1
 
 LINK LIBRARY
     NUMBER *qtan(NUMBER *x, NUMBER *eps)
-    COMPLEX *c_atan(COMPLEX *c, NUMBER *eps);
 
 SEE ALSO
     sin, cos, cot, sec, csc