Log Message:
Updated package to its latest version, 1.2.3, and cleaned up package by
adding license, making native code support conditional on the architecture as
in other OCaml packages and adding PLIST_VARS support.

Changelog (excluding bugfixes and changes to deal with new versions of other
packages):
-  1.2.1: Revised documentation
   Addition: Pxp_event.unwrap_document
   Addition: Pxp_dtd.Entity.lookup
   Addition: node method entity_id
   Addition: Pxp_event.close_entities
   Removed: Pxp_core_types_type, Pxp_type_anchor. Pxp_core_types  has now three
   submodules A, S, I taking over the roles
   Removed: E_pinstr_member. Instead, E_pinstr events are emitted
   Renaming, and addition: `Entry_content has been renamed to
   `Entry_element_content. A new `Entry_content with different  semantics has
   been added, now conforming to a standard production.
   Improvement: The parser also accepts a BOM as UTF-8 sequence.  Also, the
   autodetection of the encoding for UTF-16 has been  enhanced
-  1.2.0test*: New ~minimization option for the  [write] and [display] methods
   (user wish).
   Improvement: better control what is printed as DTD for  document#write and
   #display
-  1.1.95: Addition of ulex lexing.
   Revised namespace handling: There are now namespace_scope  objects keeping
   the scoping structure of the namespaces.  The namespace_info stuff has been
   removed. The "display"  methods can print XML while respecting the \ 
scoping
   structure.
   New exceptions Namespace_not_managed, Namespace_prefix_not_managed,
   Namespace_not_in_scope (all replacing Not_found). Methods  of
   namespace_manager may raise these exceptions.
   The event-based representation of XML is now symmetrical  to the tree-based
   representation, such that it is possible  to convert one representation into
   the other without loss.  The type of events had to be changed to achieve
   this effect.
   The new module Pxp_event contains functions for the event-based
   representation.
   Addition of pxp-pp, the PXP preprocessor.
-  1.1.94: The Pxp_reader module has been completely rewritten. This fixes some
   problems with relative URLs. - Pxp_yacc has been split up into four modules:
   Pxp_tree_parser contains now the parser API returning object trees,
   Pxp_dtd_parser is the parser API returning DTDs, Pxp_ev_parser is the
   event-based API, and Pxp_core_parser is the core of the parser. Pxp_yacc is
   still available as compatibility API. As part of the module redesign,
   Pxp_types includes now parts of its interface from Pxp_core_types_type. I
   hope this style of programming is comprehensible. - The event-based parser
   can now preprocess namespaces.
   Furthermore, there are normalization filters.
-  1.1.92: The whole lexing stuff has been restructured. There is a new tool,
   lexpp, that generates the lexers from only five files. Furthermore, much
   more 8 bit character sets are now supported as internal encodings. In
   previous versions of PXP, the internal representation of the XML trees was
   restricted to either UTF-8 or ISO-8859-1. Now, a number of additional
   encodings are supported, including the whole ISO-8859 series.
-  1.1.91: The curly braces can now even be used inside attributes, and escape
   from normal XML parsing.
   There is a new entry point Entry_expr for event-based parsing that expects
   either a single element, a single processing instruction, or a single
   comment, or whitespace. This allows more fine-grained control of what is
   parsed.
   There is now a "pull parser". In contrast to the "push \ 
parser" introduced in
   1.1.90, the calling order of parser and parser user have been inverted, i.e.
   the user calls the parser to get ("pull") the next event instead of \ 
letting
   the parser call back a user function ("push"). An interesting \ 
application is
   that O'Caml's lazy streams can be used to analyze events. An example can be
   found in examles/pullparser.
-  1.1.90: This version introduces a new event-based interface in Pxp_yacc. For
   start tags, end tags, data strings, and several other things that are found
   in the XML source so-called events are generated, and a user function is
   called for every event. See the directory examples/eventparser for examples.
   Another innovation is support for curly braces as escape characters. Inside
   elements, the left curly brace escapes from XML parsing and starts a foreign
   parser until the matching right curly brace is found:

   <element> ... { foreign syntax } ... </element>

   The curly braces are borrowed from the XQuery draft standard. They cannot
   yet be used inside attribute values. Curly braces are mostly useful in
   conjunction with event-based parsing, because it is not yet possible to
   include the "value" of the curly brace expression into XML trees.
   It is even possible to call the XML parser from the foreign parser as
   subparser. However, there not yet enough entry points for the event-based
   parser (e.g. you cannot parse just the following processing instruction,
   only misc* element misc* or whole documents are possible).