(layer 2) implement code to replace placeholders for given CSV

[ArchibaldBienetre]

CSV parsing (#4) and placeholder replacement (#5) need to be brought together.

I.e., implement a mechanism that maps a given column to a placeholder, then test this integration case (for given CSV file and text file, do replacements based on these inputs).

The actual replacement can be quite simple and string-based, e.g. reading the whole template file using IOUtils, using String#replace, then writing out a complete tex file for the final PDF rendering.

[ArchibaldBienetre]

With #43, the "bring together" part is pretty much solved.
However, we may want to wait for #5 to get resolved before we close this issue here as well.

[ArchibaldBienetre]

Close after #58