SDO client fixes

[samsamfire]

Hello,

During some testing I noticed some strange behaviour of the sdo client. ==> during block transfer it sends the "end block" after aborting. I made adjustments to the sdo client block upload : do not send the "end" block if there was an abort, client side. Also added some missing aborts. I think there some other small implementation errors here and there that I will try to send PRs for.