account_asset: clarify "Amortization" and "Depreciation"
In account_asset we mix up the terms "Amortization" and "Depreciation". @timitos and @udono are the opinion, that the term "Amortization" could be wrong in the account_asset context and being replaced by "Depreciation". Especially the report is titled "Amortization Table" but its internal name is "Asset Depreciation Table".
If you think it is ok, I will rename all the occurrences.