unittest for linux

All unittests runs with DMD 1.014 on Linux. Using this command line to compile:

rebuild -debug=UnitTest -debug -full -clean -unittest -version=UnitTest main.d tango/core/*.d tango/io/digest/*.d tango/io/model/*.d tango/io/protocol/*.d tango/io/selector/*.d tango/io/*.d tango/math/*.d tango/net/ftp/*.d tango/net/http/*.d tango/net/model/*.d tango/stdc/stringz.d tango/sys/*.d tango/text/convert/*.d tango/text/locale/Collation.d tango/text/locale/Convert.d tango/text/locale/Core.d tango/text/locale/Data.d tango/text/locale/Locale.d tango/text/locale/Parse.d tango/text/locale/Posix.d tango/text/stream/*.d tango/text/*.d tango/util/*.d tango/util/collection/model/*.d tango/util/collection/*.d tango/util/collection/iterator/*.d tango/util/collection/impl/*.d tango/util/locks/*.d tango/util/log/model/*.d tango/util/log/*.d tango/util/time/chrono/*.d tango/util/time/*.d

Will save this away in a script for later use.

Also trying with GDC 0.23 - there are problems though, noted in #454 (overview) and #461, #462, #463, #464, #465

For the future, run lib/unittest.sh to compile the unittest executable. It must be updated for additional packages, and possibly for platform differences.