Rename vars{,_init}.py -> env{,_init}.py.

This fixes some pylint 'redefined builtins' warnings.  While I was
here, I fixed the others too by renaming a few local variables.

redo/vars_init.py

@@ -1,53 +0,0 @@
-import sys, os
-
-
-is_toplevel = False
-
-
-def init_no_state():
-    global is_toplevel
-    if not os.environ.get('REDO'):
-        os.environ['REDO'] = 'NOT_DEFINED'
-        is_toplevel = True
-    if not os.environ.get('REDO_BASE'):
-        os.environ['REDO_BASE'] = 'NOT_DEFINED'
-
-
-def init(targets):
-    global is_toplevel
-    if not os.environ.get('REDO'):
-        # toplevel call to redo
-        is_toplevel = True
-        if len(targets) == 0:
-            targets.append('all')
-        exenames = [os.path.abspath(sys.argv[0]),
-                    os.path.realpath(sys.argv[0])]
-        dirnames = [os.path.dirname(p) for p in exenames]
-        trynames = ([os.path.abspath(p+'/../lib/redo') for p in dirnames] +
-                    [p+'/../redo' for p in dirnames] +
-                    dirnames)
-        seen = {}
-        dirs = []
-        for k in trynames:
-            if not seen.get(k):
-                seen[k] = 1
-                dirs.append(k)
-        os.environ['PATH'] = ':'.join(dirs) + ':' + os.environ['PATH']
-        os.environ['REDO'] = os.path.abspath(sys.argv[0])
-
-    if not os.environ.get('REDO_BASE'):
-        base = os.path.commonprefix([os.path.abspath(os.path.dirname(t))
-                                     for t in targets] + [os.getcwd()])
-        bsplit = base.split('/')
-        for i in range(len(bsplit)-1, 0, -1):
-            newbase = '/'.join(bsplit[:i])
-            if os.path.exists(newbase + '/.redo'):
-                base = newbase
-                break
-        os.environ['REDO_BASE'] = base
-        os.environ['REDO_STARTDIR'] = os.getcwd()
-
-        import state
-        state.init()
-
-    os.environ['REDO_LOCKS'] = os.environ.get('REDO_LOCKS', '')