Update Pygments to 1.6.

Version 1.6
-----------
(released Feb 3, 2013)

- Lexers added:

  * Dylan console (PR#149)
  * Logos (PR#150)
  * Shell sessions (PR#158)

- Fix guessed lexers not receiving lexer options (#838).

- Fix unquoted HTML attribute lexing in Opa (#841).

- Fixes to the Dart lexer (PR#160).

Version 1.6rc1
--------------
(released Jan 9, 2013)

- Lexers added:

  * AspectJ (PR#90)
  * AutoIt (PR#122)
  * BUGS-like languages (PR#89)
  * Ceylon (PR#86)
  * Croc (new name for MiniD)
  * CUDA (PR#75)
  * Dg (PR#116)
  * IDL (PR#115)
  * Jags (PR#89)
  * Julia (PR#61)
  * Kconfig (#711)
  * Lasso (PR#95, PR#113)
  * LiveScript (PR#84)
  * Monkey (PR#117)
  * Mscgen (PR#80)
  * NSIS scripts (PR#136)
  * OpenCOBOL (PR#72)
  * QML (PR#123)
  * Puppet (PR#133)
  * Racket (PR#94)
  * Rdoc (PR#99)
  * Robot Framework (PR#137)
  * RPM spec files (PR#124)
  * Rust (PR#67)
  * Smali (Dalvik assembly)
  * SourcePawn (PR#39)
  * Stan (PR#89)
  * Treetop (PR#125)
  * TypeScript (PR#114)
  * VGL (PR#12)
  * Visual FoxPro (#762)
  * Windows Registry (#819)
  * Xtend (PR#68)

- The HTML formatter now supports linking to tags using CTags files, when the
  python-ctags package is installed (PR#87).

- The HTML formatter now has a "linespans" option that wraps every line in a
  <span> tag with a specific id (PR#82).

- When deriving a lexer from another lexer with token definitions, definitions
  for states not in the child lexer are now inherited.  If you override a state
  in the child lexer, an "inherit" keyword has been added to insert the base
  state at that position (PR#141).

- The C family lexers now inherit token definitions from a common base class,
  removing code duplication (PR#141).

- Use "colorama" on Windows for console color output (PR#142).

- Fix Template Haskell highlighting (PR#63).

- Fix some S/R lexer errors (PR#91).

- Fix a bug in the Prolog lexer with names that start with 'is' (#810).

- Rewrite Dylan lexer, add Dylan LID lexer (PR#147).

- Add a Java quickstart document (PR#146).

- Add a "external/autopygmentize" file that can be used as .lessfilter (#802).

(obache)