Refactor global pins settings using dropdowns and add to rotary_encoder

- replace rOption by  xOption (extend option) to show default value (⎌)
- Usermod rotary_encoder: add appendConfigData function and show help and default functions
- Settings.htm: Move Usermods(pins) below the usermods

Settings_um.htm
- remove SDAPin etc
- comment check(0,k) as not used anymore
- add xOption
- add generated global pin fields (using addField) in ldS
- remove hard coded global pin fields

set.cpp: set i2c_sda etc using new generated fields
xml.cpp: set generated fields values using i2c_sda etc and show defaults

wled00/data/settings.htm

@@ -98,11 +98,11 @@
 <button type="submit" onclick="window.location='./settings/leds'">LED Preferences</button>
 <button type="submit" onclick="window.location='./settings/2D'">2D Configuration</button>
 <div id="configMenu">Loading...</div>
+<button type="submit" onclick="window.location='./settings/um'">Usermods (pins)</button> <!--WLEDMM: Move below UMs-->>
 <button type="submit" onclick="window.location='./settings/ui'">User Interface</button>
 <button id="dmxbtn" style="display: none;" type="submit" onclick="window.location='./settings/dmx'">DMX Output</button>
 <button type="submit" onclick="window.location='./settings/sync'">Sync Interfaces</button>
 <button type="submit" onclick="window.location='./settings/time'">Time & Macros</button>
-<button type="submit" onclick="window.location='./settings/um'">Usermods</button>
 <button type="submit" onclick="window.location='./settings/sec'">Security & Updates</button>
 </body>
 </html>