GPS text: added grade, cadence, temperature + some small updates

[dany123]

I have a quick note about the re-formatting rules: in the long if..else if chains with multiple lines of code inside each if block it absolutely needs a newline somewhere between each if block otherwise the entire chain looks like a huge blob of text and finding something is harder than it needs to be (see the code below line 281 in the first diff below).
For short blocks it does look nice and cozy but those are readable no matter how you write them.

[ddennedy]

looks like a huge blob of text

Maybe this is a sign that you need to refactor into more functions. You can also add comment lines as headings for sections of code perhaps followed by an empty line.

[dany123]

Comments to group some of these does sound like a pretty good workaround; I'm not sure refactoring further would be a good idea, the code would be too scattered (in this particular case).