better uniform declaration of ca._cache as global
trying to better use ca _cache in PV
allow for empty cache!
convert mca.py to use relative imports
import logging, comment out example usage
clean up use of cached PVs
restore ca.py to get_cache() function from master (for cleaner merge)
set AUTO_CLEANUP to True for Python2, False for Python3
truly better caching of PVs -- notable speed ups
use PV.wait_for_connection() in __create_PV()
fix tabs
fix tabs
use numpy.ctypeslib.as_array for ctypes Array decoding
improve ca unittest
add some timeouts to type conversion test script
tweaks to fast connection test
use relative imports for devices
version number to 3.2.4
add use_py34.bat for Windows
Merge branch 'better_pv_caching'