Add json.k to support older versions of q

If running on an old version of q, load json.k from kx to provide JSON decoding
support. With this change, reQ should be fully compatible with older versions
of kdb+; tested working with 2.8 & 3.3.

.Q.hg was only added in 3.4 - reQ will now work on prior versions that may
still be in use in some places.

json.k

@@ -0,0 +1,24 @@
+/downloaded from https://raw.githubusercontent.com/KxSystems/kdb/master/e/json.k
+
+\d .j
+
+/[]{} Cbg*xhijefcspmdznuvt
+q:"\"";s:{q,x,q};J:(($`0`1)!$`false`true;s;{$[#x;x;"null"]};s;{s@[x;&"."=8#x;:;"-"]};s)1 2 5 11 12 16h bin
+j:{$[10=abs t:@x;s@,/{$[x in r:"\t\n\r\"\\";"\\","tnr\"\\"r?x;x]}'x;99=t;"{",(","/:(j'!x),'":",'j'. x),"}";-1<t;"[",($[98=t;",\n ";","]/:.Q.fc[j']x),"]";J[-t]@$x]}
+
+/enclose
+e:{(*x),(","/:y),*|x};a:"\t\n\r\"\\";f:{$[x in a;"\\","tnr\"\\"a?x;x]}
+j:{$[10=abs t:@x;s$[|/x in a;,/f'x;x];99=t;e["{}"](j'!x),'":",'j'. x;-1<t;e["[]"].Q.fc[j']x;J[-t]@$x]}
+
+/disclose
+v:{=\~("\\"=-1_q,x)<q=x};d:{$[1<n:(s:+\v[x]*1 -1 1 -1"{}[]"?x)?0;1_'(0,&(v[x]&","=x)&1=n#s)_x:n#x;()]}
+c:{$["{"=*x;(`$c'n#'x)!c'(1+n:x?'":")_'x:d x;"["=*x;.Q.fc[c']d x;q=*x;$[1<+/v x;'`err;"",. x];"a">*x;"F"$x;"n"=*x;0n;"t"=*x]}
+k:{c x@&~v[x]&x in" \t\n\r"};
+
+\
+
+k j x:([]C:$`as`;b:01b;j:0N 2;z:0Nz,.z.z)
+k j x:"\"a \\"
+k"{},2]"
+
+

req.q

@@ -1,5 +1,7 @@
 \d .req
 
+if[.z.K<=3.1;@[system;"l json.k";{-2"Failed to load json.k: ",x}]];                 //add JSON support for older q versions
+
 cookiejar:()!()                                                                     //storage for cookies
 
 sturl:{(":"=first x)_x:$[-11=type x;string;]x}                                      //convert URL to string
@@ -112,7 +114,7 @@ send:{[m;u;hd;p] /m-method,u-url,hd-headers,p-payload
 parseresp:{[r]
   /* detect JSON reponse & parse into KDB data structure */
   / TODO - add handling for other data types? /
-  :$[r[0][`$"Content-Type"]like .h.ty[`json],"*";.j.k;] r[1];                       //check for JSON, parse if so
+  :$[(`j in key`)&r[0][`$"Content-Type"]like .h.ty[`json],"*";.j.k;] r[1];                       //check for JSON, parse if so
  }
 
 .req.get:{parseresp okstatus send[`GET;x;y;()]}                                     //get - projection with no payload & GET method