io: Fix style & add documentation in IReadFile
io: Add IDirectory

Interface for reading directories (in nutshell, a wrapper around
dirent.hin)
It is only needed for platforms, which don't have <dirent.h> *cough
cough*.
io: Fix another small inconsistency in IReadFile.h

const modifier should be placed after the type.
io: Change IDirectory method return types

This way it is simpler to handle (callee cleans up).
io: Update code style in CReadFile

Position of const modifier.
io: Create IDirectory implementation

Not tested and may not work. Also, I modified IDirectory (again)
slightly, because I found it to be not necessary to bother with
allocation.
Also, I return values and types of {IReadFile,IDirectory}::read
should be looked into before it become a mess.
Prevent 'recipe failed' when symbolic link exists

Added -f flag, so it won't give error (alternative is to tell make to
ignore this error, but I prefer this solution).
io: Fix 'missing vtable' linker error

Missing '= 0' caused following errors:
../lib/libhrplatform.so: undefined reference to `typeinfo for hrengin::io::IDirectory'
../lib/libhrplatform.so: undefined reference to `vtable for hrengin::io::IDirectory'
Because implementation for a 'non-pure' virtual turned out to be missing.
tests: Add test for IDirectory::read

Lists directory, taking it's name from stdin.
io: Fix broken CDirectory::read

Fixed incorrect usage of stat (previously it was given a pointer to
random memory location).
Changed read to output full path (relative to directory) of directory
entries.