Road to v2

[sagikazarmark]

Tracking some ideas for a potential v2 version of the library.

• Generic ToSlice (the function currently exists with a different signature)
• Remove some exotic transformations (eg. string to string slice: there are millions of ways it could work and it's quite arbitrary at the moment)
• Remove some exotic map conversions
• Inconsistent out of bounds errors #260 Better bounds checking

These aren't set in stone, just some ideas I wanted to write down.