Merge pull request #3 from tothambrus11/patch-1

Change link to website to link to docs folder

Add to_int, to_double, list_files to std/io

Update std/flags to use new string API

Update std/string API to use iterators for substring and other routines to avoid processing the entire string to find correct indexes

Add expected::with_error, tweak map_error

Add char::to_digit()

Make std/string::size() O(1) by remembering the utf length

Add bounds checking to std/vector operator []

Add sleep_for function to std/time

Add some functions to std

Merge branch 'master' of https://github.com/miki151/zenon

Add string::contains() to std

Merge branch 'master' of github.com:miki151/zenon

Change a function name