Implements zlib compression during 1st-pass

[ArtificialOwl]

with an admin settings that set the compression between 1 and 9, the chunk/zip file will be compressed during the 1st pass:

• [x] [metadata] adding the status zlib to the RestoringChunk,
• [x] switch between .zip and .zip.gz for filename based on status,
• [ ] adding the steps during the creation of the restoring point,
• [ ] adding the steps during the restoration of the restoring point,
• [x] adding the steps during the generation of a lost restoring point.

This feature will allow admin to set a compression level during the generation of backup

[cguentherTUChemnitz]

Would this implicitly enable the possibility to get multi-core compression in-place? It seems to me, that currently the point:pack command does use only one thread for compression.

[ArtificialOwl]

this feature is in standby, as the extra-time generated by the compression is a really high price for the experienced compression