fix: read upto EOF in uncompress

[rishadbaniya]

btw this wasn't an assigned task, i was curious on the uncompress and it seems it didn't read upto EOF with those dynamic code size(i.e n_bits), So this fixes it and i also added some comments, there were a lot of bitwise operation, so i thought it needed some comments

[jgarzik]

1. Very nice! This is helpful, thanks. merged.
2. Protip: It might be possible to use an existing crate for the Read-N-Bits and Write-N-Bits operations. Other file formats such as audio and video codecs have "stream of 10-bit codes" type of patterns. I meant to research this. "bitstream" might be a good search word.

[rishadbaniya]

@jgarzik, i did have the thought of looking up, but the "zero dependency goal" thing hit my head and had to go with it