fix: sqlite: string interpolation incorrectly uses backslash escapes

[shoriwe]

Patch for: #227

[shoriwe]

Here is the exact reference to the documentation:

A string constant is formed by enclosing the string in single quotes ('). A single quote within the string can be encoded by putting two single quotes in a row - as in Pascal. C-style escapes using the backslash character are not supported because they are not standard SQL.

[shoriwe]

I just added support for the other cases where interpolation is incorrectly using backslash in SQLite

[huandu]

Thanks for your contribution.

[huandu]

Some minor issues in comments.

[huandu]

@shoriwe Don't forget to fix failed cases. Thanks.

[shoriwe]

@shoriwe Don't forget to fix failed cases. Thanks.

Made all SQLite test pass by resolving to valid SQLite string syntax

[coveralls]

coverage: 96.999% (+0.02%) from 96.975%
when pulling 2994d27 on shoriwe:fix/sqlite-strings
into e4f129e on huandu:master.

[shoriwe]

@huandu. I have updated the PR, let me know if it is now ready to merge

[huandu]

LGTM.