Temporarily disable XML tests as they improperly test results

(Related: Mantis #1332)
Add rpmvercmp utility to compare RPM packages versions

This utility allows proper comparison of RPM packages versions for packages
promises (for package_version_less_command / package_version_equal_command
hooks).
Include sys/types.h to rpmvercmp to bring uint32_t into scope
Fixed namespaces description

Some sentences were incomplete or unclear.
Merge pull request #191 from zzamboni/fix/namespace-docs

Fixed namespaces description
Fix copy-paste error in documentation
Replace date +%s in testall with more widely compatible code (Mantis #1254)

In order to calculate the total run time of acceptance tests, the
testall script needs the UNIX seconds - a time() call - of the start
and end times of the test runs. It currently uses the command
"date +%s" to get these times.

Many older OS platforms - such as HP-UX 11.11, Solaris 8 and 9, and
others - do not support the "%s" format for the date command.

This patch creates a unix_seconds() subroutine which uses the modern
"date +%s" command if available, falls back to a Perl "print time()"
call, and failing that it falls back to pulling the octal date out of
a pax-created cpio header for an empty temporary file and converting
it to decimal using "bc."

This code will work on every POSIX-compliant platform (since the
pax/cpio/bc approach is strictly POSIX) as well as any platorm that
has a copy of Perl in the path.
Extend file_changes.log with information about promise handle.
master branch is open for 3.5.0
De-hardcode /tmp as a temporary directory for db_test
.mailmap for git-shortlog
ext/ subdir need to be executed
Merge pull request #193 from maciejmrowiec/master

Extend file_changes.log with information about promise handle.
Optimize WriterWriteChar for StringWriter
Add JsonPrimitiveGetAsReal
Add JsonAt
Add JsonSort, make SequenceSort take user data
Make JsonObjectGet non-const
Add JsonContainerReverse, SequenceReverse
Restore hard classes list in -v output (Redmine #1267)