company-begin-commands: Add `orgtbl-self-insert-command'

Closes #196.
Use `condition-case-unless-debug' more
company-clang-arguments: Fix default element value

Closes #200
Handle non-printable and multiple-width chars in completions

#199
company-call-backend-raw: Use `condition-case-unless-debug', too
company-dabbrev--search: Ignore "uninteresting" buffers

Closes #199
Make new tests and interactive-only

The display table is different in batch mode, I guess.
company-fill-propertize: Use `string-width' on `company-common'

It also might contain multiple-width chars.
Handle nil company-common, in order not to bind it in tests