[PATCHv2/RFC 3/3] gitweb: Create links leading to 'blame_incremental' using JavaScript

The new 'blame_incremental' view requires JavaScript to run. Not all web browsers implement JavaScript (e.g. text browsers such as Lynx), and not all users have JavaScript enabled. Therefore instead of unconditionally link to 'blame_incremental' view, we use JavaScript to convert those links to lead to view utilizing JavaScript, by adding 'js=1' to link.

The only JavaScript-aware/using view is currently 'blame_incremental'. As first, it might want to have links to non-JavaScript version, and second, it should also use window.onload, we do not add nor run fixLinks() for such views (currently hardcoded 'blame_incremental')

Possible enhancement would be to do JavaScript redirect by setting window.location instead of modifying $format and $action in git_blame_common() subroutine.

This idea was originally implemented by Petr Baudis in
  http://article.gmane.org/gmane.comp.version-control.git/47614
but it added <script> element with fixBlameLinks() function in page
header, to be added as onload event using 'onload' attribute of HTML
'body' element: <body onload="fixBlameLinks();">.  This version adds
script at then end of page (in the page footer), and uses JavaScript
'window.onload=fixLinks();'.  Also in Petr version only links marked
with 'blamelink' class were modified, and they were modified by
replacing "a=blame" by "a=blame_incremental"... which doesn't work for
path_info links, and might replace wrong part if there is "a=blame" in
project name, ref name or file name.

Slightly different solution was implemented by Martin Koegler in
  http://thread.gmane.org/gmane.comp.version-control.git/47902/focus=47905
Here GitAddLinks() function was in gitweb.js file, not as contents of
<script> element.  This might be a better solution (although I think
it would be better to split JavaScript file and load only parts that
are required).  It was also included in page header (in <head>
element) though, which means waiting for a script to load (and run).
It was smarter in that to "fix" (modify) link, it split URL, modified
value of 'a' parameter, and then recreated modified link.  It avoids
trouble with "a=blame" as substring in project name or file name, but
it doesn't work with path_info URL/link in the way it was written.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
This is nearly the same as previous (first) version, it only doesn't
have unrelated changes to blame.js that were included in earlier
version by mistake.

TODO list:
* Put fixLinks() function in gitweb.js, together with all code
  required for 'blame_incremental' view.
* Better solution to "don't invoke for JavaScript-aware actions"
  problem.  Currently hardcoded 'blame_incremental'.

  The problem to be solved is that we might want in views utilizing
  JavaScript to have fallback links to version not using JavaScript.

TODO for future commits:
* Use 'click' event to change links to jave 'js=1' parameter appended;
  this way we would check if JavaScript is enabled at the moment of
  following (clicking) link, not at the moment of loading the page.

  Unfortunately adding event listeners (much better solution than
  providing/adding 'onclick' attribute) is different in different
  browsers.

 gitweb/gitweb.perl |   21 +++++++++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)