Add soft-coded utilites to the "io" and "math" modules. The math

stuff is, for the most part, already available in the geo module; but
it's small and this naming matches the evolvoing "standard nasal
library".

Nasal/io.nas

@@ -0,0 +1,8 @@
+# Reads and returns a complete file as a string
+var readfile = func(file) {
+    if((var st = stat(file)) == nil) die("Cannot stat file: " ~ file);
+    var sz = st[7];
+    var buf = bits.buf(sz);
+    read(open(file), buf, sz);
+    return buf;
+}

Nasal/math.nas

@@ -0,0 +1,15 @@
+var abs = func(n) { n < 0 ? -n : n }
+
+var pow = func(x, y) { exp(y * ln(x)) }
+
+var mod = func(n, m) {
+    var x = n - m * int(n/m);      # int() truncates to zero, not -Inf
+    return x < 0 ? x + abs(m) : x; # ...so must handle negative n's
+}
+
+var asin = func(y) { atan2(y, sqrt(1-y*y)) }
+
+var acos = func(x) { atan2(sqrt(1-x*x), x) }
+
+var _iln10 = 1/ln(10);
+var log10 = func(x) { ln(x) * _iln10; }

Nasal/props.nas

@@ -164,7 +164,7 @@ var wrapNode = func { { parents : [Node], _g : arg[0] } }
 # Does anything ever call globals.set_props() from C++?  May need to
 # turn this into a function if so.
 #
-props.globals = wrapNode(_globals());
+var globals = wrapNode(_globals());
 
 ##
 # Sets all indexed property children to a single value.  arg[0]