Use two-digit month numbers to avoid lexicographical confusion

Even if someone interpret it as octal, there is currently no problem -
only if we compare 08 or 09 with 10 or 11 (implying a three month
release). ISO 8601 even says this is the right way of writing months!
Disallow source files with leading period

These tend to be backup files (on the form .#*#), and anyway CMake will
later consider them to not have a proper filename stem (everything is
part of the extension), leading to all sorts of strange errors.
Make without generator expressions

These are only supported from CMake >= 2.8.4; however, we can replicate
the functionality be smartly query target properties.
Use relative path function instead of string manip.

This rest-of-string functionality is not supported by older CMakes
anyway.
Provide backward-compatibility modules for older CMakes

BLAS module originally required Fortran to be enabled, newer module
doesn't; LAPACK module had some spelling errors that prevented it
from working; and cmake_push_check_state() is not available before
2.8.6.
Return name of debug files that has been stripped

These files can then be installed on the system, too.
Install debug files

As part of a -dev package, we would like to install the debug symbols
together with the headers.
Allow location of TinyXML to be specified
Test for directory existence before getting canonical path