Rename tests/ -> test/ and update internal refs.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

test/.gitignore

@@ -0,0 +1,25 @@
+*.o
+*.log
+*.trs
+.deps/
+/chomp
+/copyfile
+/dir
+/fexist
+/fisdir
+/fopenf
+/fsendfile
+/lfile
+/makepath
+/pidfile
+/printhdr
+/progress
+/rsync
+/str
+/strmatch
+/systemf
+/tempfile
+/touch
+/tree
+/which
+/yorn