* commands/configfile.c (grub_cmd_configfile): Execute the
configfile within its own context.
* include/grub/env.h (grub_env_context_open): New prototype.
(grub_env_context_close): Likewise.
* kern/env.c (grub_env): Removed.
(grub_env_sorted): Likewise.
(grub_env_context): New variable.
(grub_env_var_context): Likewise.
(grub_env_find): Search both the active context and the global
context.
(grub_env_context_open): New function.
(grub_env_context_close): Likewise.
(grub_env_insert): Likewise.
(grub_env_remove): Likewise.
(grub_env_export): Likewise.
(grub_env_set): Changed to use helper functions to avoid code
duplication.
(grub_env_iterate): Rewritten so both the current context and the
global context are being used.
* normal/command.c (export_command): New function.
(grub_command_init): Register the `export' function.