wishlist for filewatching(belongs in std)

[monkyyy]

I looked at some of the apis for file watching, allot of 1000's 
of lines of oo; its badly designed c apis blah blah blah; it 
belongs in the std. Id suggest 5 functions:

`void folderWatch(string path,void function(string) F)`
`void folderWatchAsync(string path,void function(string) F)`
`void fileWatch(string path,void function() F)`
`void fileWatchAsync(string path,void function() F)`
`bool hasFileBeenModified(string path)()//returns true once per 
file modification, first call always returns true`

Paths should be unix supporting, `..` `~`:$HOME/%appdata% 
`/`:root/C:

async version should make a thread automagicly

Passing along the full system api is irrelevant; idk why the 
implimations I saw did so

etc. etc.