Allow more than one block-id

[maxfirmbach]

Currently I run into the issue of giving different block-id's to specific regions of a mesh.
Somehow cubitpy does not allow to manually give block-id numbers for 4C input file generation as it decides internally how to assign them ...

Is it possible to change this? Or maybe is there another way that I can give block-id numbers of the 4C-input file manually?

[isteinbrecher]

The add_element_type function currently supports setting multiple block IDs by assigning consecutively numbered IDs starting from 1. Each call to the function adds a block with the next ID, allowing multiple block IDs to be defined. It should be relatively straightforward to extend this functionality to support user-specified block IDs as well.

[isteinbrecher]

Direct exo support is added with #98 , thus closing.