optimize Unicode tables

Apply optimization described in
rust-lang/regex#73 (comment)
to rust's copy of `unicode.py`.

This shrinks librustc_unicode's tables.rs from 479kB to 456kB,
and should improve performance slightly for related operations
(e.g., is_alphabetic(), is_xid_start(), etc).

In addition, pull in fix from @dscorbett's commit
d25c39f86568a147f9b7080c25711fb1f98f056a in regex, which
makes `load_properties()` more tolerant of whitespace
in the Unicode tables. (This fix does not result in any
changes to tables.rs, but could if the Unicode tables
change in the future.)

Author: kwantam

src/etc/unicode.py

@@ -25,7 +25,7 @@
 
 import fileinput, re, os, sys, operator
 
-preamble = '''// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
+preamble = '''// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -207,8 +207,8 @@ def format_table_content(f, content, indent):
 def load_properties(f, interestingprops):
     fetch(f)
     props = {}
-    re1 = re.compile("^([0-9A-F]+) +; (\w+)")
-    re2 = re.compile("^([0-9A-F]+)\.\.([0-9A-F]+) +; (\w+)")
+    re1 = re.compile("^ *([0-9A-F]+) *; *(\w+)")
+    re2 = re.compile("^ *([0-9A-F]+)\.\.([0-9A-F]+) *; *(\w+)")
 
     for line in fileinput.input(os.path.basename(f)):
         prop = None
@@ -234,6 +234,11 @@ def load_properties(f, interestingprops):
         if prop not in props:
             props[prop] = []
         props[prop].append((d_lo, d_hi))
+
+    # optimize if possible
+    for prop in props:
+        props[prop] = group_cat(ungroup_cat(props[prop]))
+
     return props
 
 # load all widths of want_widths, except those in except_cats