Move files into ext/twig.

diff --git a/.gitignore b/ext/twig/.gitignore
similarity index 100%
rename from .gitignore
rename to ext/twig/.gitignore

diff --git a/config.m4 b/ext/twig/config.m4
similarity index 100%
rename from config.m4
rename to ext/twig/config.m4

diff --git a/php_twig.h b/ext/twig/php_twig.h
similarity index 100%
rename from php_twig.h
rename to ext/twig/php_twig.h

diff --git a/twig.c b/ext/twig/twig.c
similarity index 100%
rename from twig.c
rename to ext/twig/twig.c