Add config option for transcendental BASIC functions

Also move all transcendental functions to a separate source directory
Turn off these functions for all configurations for now

src/basic/math_trans/poly_atn.s

@@ -0,0 +1,30 @@
+;; #LAYOUT# STD *       #TAKE
+;; #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
+;; #LAYOUT# *  BASIC_0  #TAKE
+;; #LAYOUT# *   *       #IGNORE
+
+; Polynomial for the atn function
+
+
+!ifdef CONFIG_TRANSCENDENTAL_FUNCTIONS {
+
+
+poly_atn:
+
+    !byte $0B                          ; series length - 1
+
+    +PUT_CONST_POLY_ATN_1
+    +PUT_CONST_POLY_ATN_2
+    +PUT_CONST_POLY_ATN_3
+    +PUT_CONST_POLY_ATN_4
+    +PUT_CONST_POLY_ATN_5
+    +PUT_CONST_POLY_ATN_6
+    +PUT_CONST_POLY_ATN_7
+    +PUT_CONST_POLY_ATN_8
+    +PUT_CONST_POLY_ATN_9
+    +PUT_CONST_POLY_ATN_10
+    +PUT_CONST_POLY_ATN_11
+    +PUT_CONST_POLY_ATN_12
+
+
+}