xml comma bugfix + few string optimisations

[blazoncek]

fix for incorrect JSON array creation.

[netmindz]

Can you please provide a little more info on what what the impact of this issue was so others know how to test your fix and also establish if it needs to be merged before the release candidate is tagged

[blazoncek]

Sorry.
The JSON array for reserved pins (settings page) was incorrectly constructed (wrong order of commas) in some cases (Ethernet). It should be included in 0.15.0 release.
I also added a few string optimisations to reduce image size.

[netmindz]

Thank you for that further information, but I must confess that I am still unclear on what was wrong or how to reproduce the error. I find examples really helpful

[willmmiles]

Thank you for that further information, but I must confess that I am still unclear on what was wrong or how to reproduce the error. I find examples really helpful

The bug is a code inconsistency on whether the commas in the reserved pin list ought to be added first or last. The "disallowed" pins added commas after, but other cases (DMX, hardwareTx, wired Ethernet) would add a comma first, so the list would end up reading d.rsvd=[1,2,,3,4,5] -- note extra comma in the middle. To reproduce the issue, make a build with WLED_ENABLE_DMX, WLED_DEBUG, or WLED_USE_ETHERNET and inspect the settings output, eg. http://wled.local/settings/s.js?p=2

That said: while not technically correct, in my prior testing, the UI did seem to handle the empty element gracefully.

[willmmiles]

Generally looks good to me and passes my functional tests.