Improve support for special characters in values for omlzip.

[NicolasRouquette]

The suggestion is as follows:

• Split the string on any of \n, \r, ", keeping he splitting character.
• Produce an array of either special strings or normal strings.
• A special string is one of the following: "\n", "\r", "\""

Example:

This is a special quote:
"Special characters are a pain!"

This would yield the following array:

["This is a special quote:", "\n", "\"", "Special characters are a pain!", "\""]

[NicolasRouquette]

For serialization/deserialization, an alternative could be Base64 encoding/decoding.

However, this is undesirable because the omlzip format is intended to support precise differences in GIT. If we were to encode raw strings in Base64, we'd have to have a non-trivial utility to diff encoded raw strings.