Moved float str buffer constants to the strconv module
pre-rebase commit
Switched over a bunch of splitting funktions to non-allocating iterators
Isolated bug, static vector seems to behave differently than fixed sized one
Fixed all use sites and tests
Added missing lifetime annotations, doc and whitespace cleanups
Added more missing lifetime annotations
auto merge of #5555 : Kimundi/rust/str-dealloc-3, r=catamorphism

- Most functions that used to return `~[~str]` for a list of substrings got turned into iterators over `&str` slices
- Some cleanup of apis, docs and code layout