Settings validation refactoring (#964)

* Rewrite the setting API to use same API as ESP3D-TFT or at least close enough to be improved - WIP

* Add isValidXXX setting API

* Factorize dispatch_setting for ESP400

* ESP400 refactoring

docs/pagespliter.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+
+import os
+
+input_file = "espXXX.md"
+output_file_head = "esp"
+output_ext = ".md"
+
+
+   
+f = open(input_file, "r")
+lines = f.readlines()
+#parse each lines
+head = ""
+have_command = False
+fo=0
+count = 0
+for line in lines:
+    if not have_command:
+      count=0
+      head+=line
+      if line.startswith("title ="):
+        have_command = True
+        num = line.split("ESP")[1].split("]")[0]
+        fo = open(output_file_head+num+output_ext, "w")
+        fo.write(head)
+        have_command = True
+    else:    
+          if line.startswith("+++"):
+              count+=1
+              if count==2:
+                fo.close()
+                have_command = False
+                head = line
+                print("close file "+output_file_head+num+output_ext)
+              else:
+                fo.write(line)
+          else:
+              fo.write(line)
+         
+f.close()