fix: IconFlipped.getMinV

Prev. state:
```java
return this.flipV ? this.baseIcon.getMinV() : this.baseIcon.getMinV();
```
which is an obvious typo.
Now:
```java
return this.flipV ? this.baseIcon.getMaxV() : this.baseIcon.getMinV();
```

As a tiny bonus, added line about 'gradle genPatches' to readme