nicer "find in file output", using pango markup

* highlights grep matches and also groups results by files.
* msgwin_msg_add() api is unchanged but text is converted to markup
internally.
* added msgwin_msg_add_markup() and msgwin_msg_add_markup_no_validate().
* added utils_utf8_make_valid() and force valid utf8 in the GTK
widgets, fixes some warnings.
* do not process too many grep results at once to give a chance
to the UI to handle some events sometimes.
do not highlight regex results, highlight case insisentive results
adding multi tab 'find in files'
use defines for buttons
make clicking previous search results work

* we cannot afford a global msgwin.messages_dir now since there are
multiple tabs
"Find in files": pressing Enter in the directory entry now triggers the
search
add a button to set the search path to the current directory
ooops, revert testign
Fix sign comparison warning

Since the previous line ensured len is < 100, just casting it is fine.
multi_tab_fif: allow to close tabs
splitwindow: Change wording for keybinding to by in sync with tools-menu entries. Should fix #102
PHP: Fix parsing of anonymous functions returning a reference
PHP: Fix parsing of anonymous functions using the "use" keyword

http://www.php.net/manual/en/language.namespaces.php#104136
Use proper string comparison for portability
Fix gcc warning 'cast to pointer from integer of different size'
Fix warning 'comparison between signed and unsigned integer expressions'

With gcc on Windows.
Fix full hashing on 64-bit platforms
Merge branch 'multi_tab_fif'
adding a README.md