Replace search function with a better search

[addiks]

Currently the project-index-search is slow. That is because it just executes a sequence of SQL select statements performing full-text-searches on several columns of the raw tables of the project-index.

There should be a dedicated data-structure for the project-search to improve the runtime-performance of the search. This new data-structure should also allow a more fuzzy search for a more misspell-tolerant search.