Fixed memory leak in aacgmConvArr()

Changed PyList_Append to PyList_SetItem since PyList_Append can cause a memory leak (as per http://stackoverflow.com/questions/3512414/does-this-pylist-appendlist-py-buildvalue-leak). Also changed format string of Py_BuildValue from "OOO" to "NNN" since "O" will increment the reference count (http://docs.python.org/release/1.5.2/ext/buildValue.html) and this can cause a memory leak too (http://stackoverflow.com/questions/5508904/c-extension-in-python-return-py-buildvalue-memory-leak-problem).
Merge branch 'patch-7' of https://github.com/asreimer/davitpy-usask into development
updated mac instructions for homebrew users
Merge branch 'master' of https://github.com/vtsuperdarn/davitpy into development
fixed units problem and longitude wrap-around in greatCircleMove()
added figure option to plotRti()
added more control to xticks, yticks, axvlines in plotRti()
Merge remote-tracking branch 'upstream/master'

Conflicts:
	pydarn/plotting/rti.py