Introduce a new type to replace off_t called wt_off_t since off_t is 32-bits on Windows regardless of target architecture
Merge branch 'wt_off_t' of https://github.com/markbenvenuto/wiredtiger into markbenvenuto-wt_off_t

Conflicts:
	src/conn/conn_api.c
Typedef wt_off_t as an  off_t if the type is available on the system.
Fix long lines.
Merge branch 'markbenvenuto-wt_off_t' into develop