cmake conversion #1

Don't feel at ease with this one.
I couldn't build It with automake, so this is built with cmake right from the get-go.
The heimdal package (which is needed for libtdeldap) provided by slackbuilds locked me out of my root account through the 'su' command till I figured out what was going on.
The 'doc' folder is actually empty.
There is no *.po files in the 'po' folder, I've added a CMakeLists.txt nonetheless.
Waiting for your comments Slavek.

I'll change 'requested' to 'required' after your comments.

Yes, right, requested => required would have my comment 😸 However, because I encountered some other problems, I solved it in a subsequent patch:

On Debian, some include are still in the subdirectory ${TDE_INCLUDE_DIR}/tde.
Include files for kerberos may be in a special directory – for example, to allow both MIT and Heimdal to be installed concurrently. So I added the KRB5 library detection and ${KRB5_INCLUDE_DIRS}.
Traditional problem with includes in UI files.
Occasional problem with improper automoc.
Unexpectedly different solution for TQT_NO_ASCII_CAST.

In any case, your base was good.