adding support for tab-separated translations

[dayjaby]

With this small update, yomichan scans the entire line for a tab character. If it finds one, it treats the rest of the line as translation.

E.g. having the line 彼は洞察力のある人だ。\t"He is a man of vision." 彼は洞察力のある人だ。 becomes the definition's sentence "He is a man of vision." becomes the definition's translation.

The proper field for the translation can be set in the preferences with {translation}. I made this update mainly to be able to import sentence lists from tatoeba.com more easily, because they export it with the same pattern like the example above.

[FooSoft]

Thanks for the pull request. Before I accept it, please make the following two changes to your code:

• Instead of using two for loops to search for the tab and newline character use the built in string methods find and rfind. There is no need to write code for functionality already built into the standard library.
• Variables translation_start and translation_end should be named translationStart and translationEnd to be consistent with the camel-case naming convention for variables in the rest of the code.

[dayjaby]

Thanks for having a look at it! I fixed the mentioned points.

[FooSoft]

Merged, thanks for the codes ^^