Add init keyword pass through?

[azaroth42]

Further to #6, it would be valuable to allow pass-through of keywords on the Lmdb.open() function to the Environment's constructor. Then we could do:

cxn = Lmdb.open('file.lmdb', readahead=False)

for example.

It's currently hard to override the open function on a subclass if you want to respect n as a flag, as the module doesn't export the remove_lmdbm() function.

[Dobatymo]

@azaroth42 I will add a way to passthrough keywords. And you can import the remove function like this from lmdbm.lmdbm import remove_lmdbm

[Dobatymo]

Fixed https://github.com/Dobatymo/lmdb-python-dbm/releases/tag/v0.0.6