Fixed the regexp validating USE flag names
Upgrade admin/gentoo/puse to v0.2

* Increased parameterization of the code to handle various operating modes:
** package.use file ('use' mode)
** package.accept_keywords ('key' mode)
** package.license ('lic' mode)
* Minor fixes:
** regexp characters in flag names
** 'die' proc for error messages
** only display updated flags in verbose mode (still not happy about the
   looks of this output though)
* NO change to the program logic otherwise (but all references to 'USE
  flags' where replaced with the 'flags' wording so it looks like a lot
  of changes were made)
Minor fixes in admin/gentoo/puse

* escaped some unescaped variables in regexps
* fixed an empty lsearch command
Removed the obsolete admin/gentoo/addkeyword-package.sh script (obsoleted by admin/gentoo/pkey)