Training UI Changes

[dfaker]

Mostly just usability when I've been going around these screens and making stupid errors, or having to restart.

Use an existing caption file is for https://github.com/dfaker/quick-ti-cropper where I've got it to spit out tagged directory names, but other tooling can use the same approach.

Splits training rate into two inputs one for hypernetworks one for embeddings:

Adds option to use an existing caption file, and define how it's input is to be used:

Adds overwtite old option when creating hypernetworks or embeddings.

Fixes a reference to 'last embedding' in hypernetwork training html output.

Adds wiki link to training header text: