this PR adds long prompt support and enables compel's new `.and()`
concatenation feature which improves image quality especially with SD2.1
example of a long prompt:
> a moist sloppy pindlesackboy sloppy hamblin' bogomadong, Clem Fandango
is pissed-off, Wario's Woods in background, making a noise like
ga-woink-a
the same prompt broken into fragments and concatenated using `.and()`
(syntax works like `.blend()`):
```
("a moist sloppy pindlesackboy sloppy hamblin' bogomadong",
"Clem Fandango is pissed-off",
"Wario's Woods in background",
"making a noise like ga-woink-a").and()
```
and a less silly example:
> A dream of a distant galaxy, by Caspar David Friedrich, matte
painting, trending on artstation, HQ
the same prompt broken into two fragments and concatenated:
```
("A dream of a distant galaxy, by Caspar David Friedrich, matte painting",
"trending on artstation, HQ").and()
```
as with `.blend()` you can also weight the parts eg `("a man eating an
apple", "sitting on the roof of a car", "high quality, trending on
artstation, 8K UHD").and(1, 0.5, 0.5)` which will assign weight `1` to
`a man eating an apple` and `0.5` to `sitting on the roof of a car` and
`high quality, trending on artstation, 8K UHD`.
