"align: center" doesn't center my block properly

[rvdz]

If the slack size is not equals to zero, I can't center perfectly my blocks on the bar as the slack size will be added when the position of the block is computed.

[rvdz]

I found a clue to fix this. In the function ya_create_block, around line 113, I removed an extra blk->bar->slack added value and it seems to work fine.

[NBonaparte]

Feel free to make a pull request and we can work from there.

[romzie]

Issue still not fixed on Debian 9.3 with yabar v0.4.0-1 installed with apt install yabar