Add lyrics exercises

[keiravillekode]

• house
• twelve-days
• bottle-song
• food-chain
• proverb

Each has a string (offset, length) as the output, with a newline at the end of each line.

Each accepts two i32 as input, apart from proverb, which accepts a string (offset, length), where each word in the string is followed by a newline. Example: MIPS

• crypto-square

This has a string (offset, length) as input and a string (offset, length) as output, e.g.

"imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn  sseoau "

Generating the output in-place would be difficult, so I won't include the common

The input string can be modified in place if desired.