Rewrite array parsing to handle multiple preservation settings

Problem/Motivation

Rewrite array parsing to handle multiple preservation settings. The current array parsing code is probably the least elegant in the whole project and duplicates significant pieces of code in the expression builder routine. Revise this to take advantage of the expression builder while better preserving whitespace and comments.

Proposed resolution

See patch(es).

Remaining tasks

Before committing, code will be reviewed, tested against D8 core files, and documentation updated.

User interface changes

Not applicable.

API changes

To be completed later.