Add dfhack.printall_recurse to quickly print df containers

I often want to see multiple items quickly when trying to figure out
what states actually matter to an issue that I debug. I decided to make
it easier to quickly dump df structures with substructures and
containers. It will generate large amount of data which can be sometimes
slow to process manually. But processing can be automated using
dfhack-run lua ^<df data to inspect> and pipe to other tools (eg grep,
sed, perl, sort, uniq etc)

library/lua/dfhack.lua

@@ -180,6 +180,116 @@ function printall_ipairs(table)
     end
 end
 
+local do_print_recurse
+
+local function print_string(printfn, v, seen, indent)
+    local str = tostring(v)
+    printfn(str)
+    return #str;
+end
+
+local fill_chars = {
+    __index = function(table, key, value)
+        local rv = string.rep(' ', 23 - key) .. ' = '
+        rawset(table, key, rv)
+        return rv
+    end,
+}
+
+setmetatable(fill_chars, fill_chars)
+
+local function print_fields(value, seen, indent, prefix)
+    local ok,f,t,k = pcall(pairs,value)
+    if not ok then
+        dfhack.print(prefix)
+        dfhack.println('<Type doesn\'t support iteration with pairs>')
+        return 0
+    end
+    local prev_value = "not a value"
+    local repeated = 0
+    for k, v in f,t,k do
+        -- Only show set values of bitfields
+        if value._kind ~= "bitfield" or v then
+            local continue = false
+            if type(k) == "number" then
+                if prev_value == v then
+                    repeated = repeated + 1
+                    continue = true
+                else
+                    prev_value = v
+                end
+            else
+                prev_value = "not a value"
+            end
+            if not continue then
+                if repeated > 0 then
+                    dfhack.println(prefix .. "<Repeated " .. repeated .. " times>")
+                    repeated = 0
+                end
+                dfhack.print(prefix)
+                local len = do_print_recurse(dfhack.print, k, seen, indent + 1)
+                dfhack.print(fill_chars[len <= 23 and len or 23])
+                do_print_recurse(dfhack.println, v, seen, indent + 1)
+            end
+        end
+    end
+    if repeated > 0 then
+        dfhack.println(prefix .. "<Repeated " .. repeated .. " times>")
+    end
+    return 0
+end
+
+-- This should be same as print_array but userdata doesn't compare equal even if
+-- they hold same pointer.
+local function print_userdata(printfn, value, seen, indent)
+    local prefix = string.rep('    ', indent)
+    local strvalue = tostring(value)
+    dfhack.println(strvalue)
+    if seen[strvalue] then
+        dfhack.print(prefix)
+        dfhack.println('<Cyclic reference! Skipping fields>\n')
+        return 0
+    end
+    seen[strvalue] = true
+    return print_fields(value, seen, indent, prefix)
+end
+
+local function print_array(printfn, value, seen, indent)
+    local prefix = string.rep('    ', indent)
+    dfhack.println(tostring(value))
+    if seen[value] then
+        dfhack.print(prefix)
+        dfhack.println('<Cyclic reference! skipping fields>\n')
+        return 0
+    end
+    seen[value] = true
+    return print_fields(value, seen, indent, prefix)
+end
+
+local recurse_type_map = {
+    number = print_string,
+    string = print_string,
+    boolean = print_string,
+    ['function'] = print_string,
+    ['nil'] = print_string,
+    userdata = print_userdata,
+    table = print_array,
+}
+
+do_print_recurse = function(printfn, value, seen, indent)
+    local t = type(value)
+    if not recurse_type_map[t] then
+        printfn("Unknown type " .. t .. " " .. tostring(value))
+        return
+    end
+    return recurse_type_map[t](printfn, value, seen, indent)
+end
+
+function printall_recurse(value)
+    local seen = {}
+    do_print_recurse(dfhack.println, value, seen, 0)
+end
+
 function copyall(table)
     local rv = {}
     for k,v in pairs(table) do rv[k] = v end
@@ -334,6 +444,7 @@ function dfhack.interpreter(prompt,hfile,env)
               " '= foo' => '_1,_2,... = foo'\n"..
               " '! foo' => 'print(foo)'\n"..
               " '~ foo' => 'printall(foo)'\n"..
+              " '^ foo' => 'printall_recurse(foo)'\n"..
               " '@ foo' => 'printall_ipairs(foo)'\n"..
               "All of these save the first result as '_'.")
         print_banner = false
@@ -358,6 +469,9 @@ function dfhack.interpreter(prompt,hfile,env)
             print(table.unpack(data,2,data.n))
             printall_ipairs(data[2])
         end,
+        ['^'] = function(data)
+            printall_recurse(data[2])
+        end,
         ['='] = function(data)
             for i=2,data.n do
                 local varname = '_'..vcnt