Update automake to 1.14

* configure.ac: Bump automake version to 1.14.
* tests/Makefile.am: Update to use new test driver API.
* build-aux/autogen.sh: Remove build-aux/compile during cleanup.
Properly initialize base code sentinel in make_tree()

* src/decode.c (make_tree): make sure that base code sentinel
(base[21]) is always set to plus infinity.  Fixes #12.
Add test case for bug #12 (rhbz#1017957)
Fix a typo in tests/codelen20.c
Fix another typo in tests/codelen20.c
Avoid integer overflow with some 32-bit versions of Perl

build-aux/make-crctab.pl: Avoid using arthmetic operators
in favor of bit shift and immediate constants.
Explain existence of two different block parsing algorithms
Remove dead code

* src/parse.c (parse): Remove code that is executed
  under condition that is asserted to be false.
Document block header parsing functions
Document code in process.h
Add reproducer for parser bug
Rewrite Package-Merge

* src/encode.c (package_merge): Rewrite from scratch basing on
Java implementation in lbzip2-java.
Fix parser bug (overrun2)

* src/parse.c (parse): Backport parser bugfix from lbzip2-java
commit 4424921.
Update copyright notices
Add .gitignore files
Remove old implementation of Package-Merge
Compute cost when assigning prefix code
Port new Package-Merge implementation from Java
Integrate Package-Merge with encoder
Make variables names in prefix encoder more human-readable