Add complex search queries to site search

[cmcknight]

Minisearch has the capability of using an AST-like data structure that supports complex queries.

Example: (cutting or welding) and torch

The query above would only return items that match either 'cutting' or 'welding' but also have the term 'torch'. With the current searchbar, this will require the construction of a parser to generate the appropriate data structure.

See Advanced Combination of Queries for details on the data structure.