Update lmdb_ext.h

Recent gcc complains that redefinition of typedef Transaction is not allowed - removed the extra typedef.
Merge pull request #4 from nwpierce/patch-1

Update lmdb_ext.h - remove duplicate Transaction typedef
work on compatibility
liblmdb update
Merge branch 'master' of github.com:minad/mdb
fix
not impl
update readme

[ci skip]
README: add require

[ci skip]
update readme

[ci skip]
v0.3.1
typo

[ci skip]
add badges

[ci skip]