#28 implicit literal string concatenation

[Toyotomi Hideyoshi]

I found a very annoying bug in some of my code due to
a missing comma in a list defined as follows:

>>> [
... 'dir1/','dir2/'
... 'dir3/'
... ]
['dir1/', 'dir2/dir3/']

Note the missing comma are 'dir2/'

>>> 'foo/''bar'
'foo/bar'

>>> 'foo''bar'
'foobar'

It would be nice if pychecker detected one of these
cases.