Introduce AtomicFile and a test of this module to the code.
AtomicFile is like File, except all writes go to temporary files until
the class method finalize_all () is called and the temporary files are
copied over the real files. If any writes fail, like when there is no
more space on the filesystem, none of the files in the database will be
modified.
Since we need version 1.00 of libfiu, I have only added it to the debian
testing container, which includes libfiu-1.00 in the default repository.
Related to #155
This commit implements (after the example of taskwarrior) a Travis-based
multi-OS continuous integration service, that tests on a variety of
Linux-based hosts and Mac OS X.
