This reverts commit 16860fb6.

merge-cores option: puts together all files of a project into a single 'archive'. For convenience of Windows users :)

There was a quasi-bug that caused that
hdlmake was trying to remove some submodules
after thier parent modules were removed. This
generated error messages. Now the modules are
removed in reverse order compared to fetching

Until now it was sometimes necessary to run
hdlmake multiple times in order to fetch specified
modules. This bug is now fixed and a single
run is needed.

There was a bug fixed because of which hdl-make
didn't work properly without specifying run
parameters (there was no default action)

--list enables people to list content of their modules.
Indentation makes easier visual recognition of the
content.

Proper ISE version is detetcted basing on XILINX variable.
Afterwards, a path to ISE installtion (default) is put
into the makefile.