Clarify README instructions

Note that posting to the mailing list does not need subscription.
Clearly split the software requirements for the source from git and
the source from a tarball. Mention what functionality the compression
libraries replace, and merge redundant project names. Make explicit
that the curses library requirement can be lifted when disabling
dselect. Distinguish between additional documentation and translated
documentation. Add some basic instructions on how to configure and
make.

README

@@ -24,7 +24,7 @@ The subscription interface and web archives can be found at:
 
   <http://lists.debian.org/debian-dpkg/>
 
-The mailing list address is:
+The mailing list address is (no subscription required to post):
 
   debian-dpkg@lists.debian.org
 
@@ -39,62 +39,64 @@ Source Repository
 Building from git source
 ------------------------
 
-To prepare the source tree before starting the build process, some software
-needs to be installed, additional software might provide optional features.
+To prepare the dpkg source tree from git before starting the build process
+some required software needs to be installed:
+
+  GNU autoconf >= 2.60
+  GNU automake >= 1.8
+  GNU gettext >= 0.18 (or just autopoint if using --disable-nls)
+  flex
+
+After installing the needed software, and running the following command on
+the git tree:
+
+  $ autoreconf -f -i
+
+the source should be roughly equivalent to the distributed tar source.
 
-The minimum software required to build dpkg is:
+
+Building from tar source
+------------------------
+
+The minimum software required to configure and build dpkg from a tarball is:
 
   C89 compiler with few C99 extensions (see doc/coding-style.txt)
   GNU make
-  GNU autoconf >= 2.60
-  GNU automake >= 1.8
-  GNU gettext  >= 0.18
   pkg-config
-  flex
   perl
 
+To enable optional functionality or programs, this software might be needed:
+
+  zlib (used instead of gzip command-line tool)
+  xz's liblzma (used instead of xz command-line tool)
+  libbzip2 (used instead of bzip2 command-line tool)
+  libselinux
+  curses compatible library (needed on --with-dselect)
+
 To run the test suite («make check»):
 
   TimeDate perl module
   IO-String perl module
 
-To enable optional functionality or programs, this software might be needed:
-
-  zlib (used instead of the command-line tool)
-  liblzma (from the xz project; used instead of the command-line tool)
-  libbzip2 (from the bzip2 project; used instead of the command-line tool)
-  libselinux (needed for SELinux support)
-  curses compatible library (needed for dselect)
-
-To enable translated or additional («make doc») documentation this
-software will be needed:
+To enable additional developer's documentation («make doc») this software
+will be needed:
 
-  po4a >= 0.36.4 (>= 0.41 for VPATH builds)
   pod2man
   doxygen
   dot
 
+To enable translated documentation this software will be needed:
+
+  po4a >= 0.36.4 (>= 0.41 for VPATH builds)
+
 To enable code coverage («./configure --enable-coverage; make coverage»)
 this software is needed:
 
   lcov (from the Linux Test Project)
   Devel-Cover perl module
 
-
-After installing the needed software, and running the following command on
-the git tree:
-
-  $ autoreconf -f -i
-
-the source should be equivalent to the distributed tar source.
-
-
-Building from tar source
-------------------------
-
-The instructions to build the distributed source are included in the
-INSTALL file.
-
+The build process is done by running the usual «./configure; make». To
+see all available configuration options please run «./configure --help».
 The following configure options might be of interest to disable specific
 programs:
 
@@ -108,5 +110,3 @@ And the following to disable modifications to the build flags:
   --disable-compiler-warnings
   --disable-compiler-optimisations
   --disable-linker-optimisations
-
-To see all available configuration options please run «./configure --help».