OcdFileImport: Handle text objects without termination

[dl3sdo]

As some .ocd files contain text objects without terminating null character limit the search for a terminating null character to the data area of the string. Closes #2206

[dg0yt]

I understood #2206 as indicating a problem with saving OCD files, not with loading OCD files. We do fill remain space with zero, but what if we didn't reserve extra space? https://github.com/OpenOrienteering/mapper/blob/d42dbf49ec4fea4fd9389426b57ac485614bd795/src/fileformats/ocd_file_export.cpp#L3117-L3121

[dl3sdo]

Hello Kai, you are absolutely right. The error is caused by an invalid export in Mapper which can easily be reproduced for every text object with a multiple of 32 characters. I apologize for not having read the issue description carefully enough where it was stated that the .ocd files had been created by Mapper. I will create a new PR (which should just contain an additional '+ 1').

[lpechacek]

@dl3sdo, while reading through the patch, I noticed that OcdFileImport::getObjectText() functionality is implemented twice. The OCD v8 version is correct while the generic version is buggy. I suggest that we reuse the v8 code for all the format versions.

Example implementation is at https://github.com/lpechacek/mapper/commits/issue-2206-garbage-in-text/.

[dl3sdo]

Libor, you are absolutely right, it makes little sense to have two implementations.

[dg0yt]

Closing in favor of https://github.com/OpenOrienteering/mapper/pull/2219.