Add case transform

[Weisl]

Transforming Case in Replacement

\U$1
Uppercase the first group
hello-world → HELLOworld
\L$1
Lowercase the first group
HELLO-WORLD → helloWORLD
\u$1
Uppercase first letter of group
hello-world → HelloWorld
\l$1
Lowercase first letter of group
HELLO-WORLD → hELLOWORLD