Updated to Yara 2.1.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	Makefile.am
	README.md
	config.h
	configure.ac
	doc/YARA User's Manual.pdf
	libyara/Makefile.am
	yara-python/setup.py
	yara-python/setupwin32.py
	yara-python/setupwin64.py
	yara-python/tests.py