Major infrastructure changes, part 2.

* Moved helpers, common and triggers dirs into xbps-src, where
  they belong.
* Renamed the templates dir to srcpkgs, it was so redundant before.
* Make it possible to add subpkgs with no restriction in names, for
  example udev now has a subpkgs called "libgudev". Previously
  subpkgs were named "${sourcepkg}-${pkgname}".
* xbps-src: changed to look for template files in current directory.
  That means that most arguments from the targets have been removed.
* xbps-src: added a reinstall target, to remove + install.
* xbps-src: do not overwrite binpkgs by default, skip them.

And more that I forgot because it's a mega-commit that I've been
working for some days already...

--HG--
extra : convert_revision : 0f466878584d1e6895d2a234f07ea1b2d1e61b3e

templates/tcp_wrappers/patches/fix_build_scaffold.c.diff

@@ -1,10 +0,0 @@
---- scaffold.c	1997-03-21 10:27:24.000000000 -0800
-+++ scaffold.c	2004-05-07 19:44:50.000000000 -0700
-@@ -25,7 +25,6 @@
- #define	INADDR_NONE	(-1)		/* XXX should be 0xffffffff */
- #endif
- 
--extern char *malloc();
- 
- /* Application-specific. */
-