Wrong tab stop position after full width characters result in clobbering of earlier characters
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### Versions
ConEmu build: 190310 x64
OS version: Windows 10 1809 (17763.379) x64
Used shell version: PowerShell 5.1.17763.316
### Problem description
Tab stop position calculations seem to treat full-width characters as single width, resulting in wrong tab stop positions that clobber earlier characters. A very simple example:
```powershell
$ echo "一二三四五六七`t123"
```
The output looks like this:
<img width="280" alt="clobber" src="https://user-images.githubusercontent.com/4149852/54469103-af379000-47ce-11e9-9b18-b160610c2548.png">
### Additional files
[Settings](https://gist.githubusercontent.com/zmwangx/acb0f5fa88f48680b611bf0f7a8ee59b/raw/ead8515c554e78080e92efaf61e6e7dda7f4f13c/ConEmu.xml)
Please let me know if logs are necessary.