Add Q and q formatters to buffer/format.

These are similar to P and p, but print values
on a single line for a much more compact version.

src/include/janet.h

@@ -1262,6 +1262,7 @@ JANET_API int janet_verify(JanetFuncDef *def);
 
 /* Pretty printing */
 #define JANET_PRETTY_COLOR 1
+#define JANET_PRETTY_ONELINE 2
 JANET_API JanetBuffer *janet_pretty(JanetBuffer *buffer, int depth, int flags, Janet x);
 
 /* Misc */