fix wrong String.at/2 output when second arg is not an integer
Merge pull request #2877 from jw2013/string

fix wrong String.at/2 output when second arg is not an integer
explains when to use Float.parse/1 and that String.to_float will not deal with integer fmt strings
bypass warning
fix mistake on test
fix doc line's length and test one more time
Merge pull request #2873 from eksperimental/float

improve and examples for Float.parse/1 and String.to_float
Fix SupervisorTest :push handle_cast method

* handle_cast/2 does not take 'from' param
Merge pull request #2878 from akira/supervisor_test_fix

Fix SupervisorTest :push handle_cast method
Move 0 index match to the function head in `String.split_at/2`
Move same pos match to the function head in `Regex.apply_list/5`
Merge pull request #2879 from lexmag/move-to-fun-heads

Move guards to fun heads
rename two identical variables to same name and remove guard
Merge pull request #2881 from jw2013/string

rename two identical variables to same name and remove guard