Let `perlbre alias help` means `perlbrew help alias`.
Preserve the execution order for `exec` command if `--with` option is given.

Even if the content contain duplicate items.

Closes GH #297
Remove the `uniq` subroutine, which is not used in the pm code anymore.
require the latest version of CPAN::Perl::Releases
Unalias grep command

Escape sequences are written to '$PERLBREW_HOME/init' if user defines
grep alias like "alias grep='grep --color=always'".
Merge pull request #307 from syohex/unalias-grep

Unalias grep command
remove debug-purposes statement.
Fix 'list-modules' when current env is with a lib, so that the output correctly list all modules inside a lib.
update changelog
Merge branch 'release/0.61' into develop

Conflicts:
	Changes
update change log.
version bump.
rebuild 0.62 standalone executable.
Merge branch 'release/0.62'