hush: rework variable storage and environment handling.
More that -100 bytes of code + memory leak plugged.
Added a testcase for it.

diff --git a/shell/README b/shell/README
index a9b4346..a09353d 100644
--- a/shell/README
+++ b/shell/README
@@ -1,6 +1,10 @@
 Various bits of what is known about busybox shells, in no particular order.
 
 2007-05-24
+hush: environment-related memory leak plugged, with net code size
+decrease.
+
+2007-05-24
 hush: '( echo ${name )' will show syntax error message, but prompt
 doesn't return (need to press <enter>). Pressing Ctrl-C, <enter>,
 '( echo ${name )' again, Ctrl-C segfaults.