Use new data folder, and test file_to_directory().

Created a Data folder that contains testfiles to be used in testcases,
Now each test methods that require these files will copy them from the
Data/ folder before actually using them, this allows us to reuse data
files with different names.

Added a 2 test methods for file_to_directory(). First check if it
creates anything and second check if the file it created is a directory.
Fix creation of tmp files.

file_to_directory() and directory_to_file() both checked for .bkp.%d file
when creating trying to create .tmp.%d files. Fix it so they check for
.tmp.%d instead.
Add test case for directory_to_file()

Added a testcase for directory_to_file(), same as the last commit checks
for the creation of a file and its type.

Also added Data files necessary for this test.
Discard functino names from test method names.

Renamed test methods without the name of the function they are testing
for, since the function name is used as the class name there was no need
to repeat it.
Test data integrity after file/directory convertion.

Added 2 test methods for directory_to_file() and file_to_directory() to
make sure the rules are the same after the convertion.
Ignore ~ and ! in categories.