+ added search.h
* updated common.h: added regex and search headers
+ added REGEX_SEARCH build option
* changed search_t struct
+ added search_free() prototype
* renamed function parse_search_tags -> parse_search_terms
+ implemented parse_search_terms()
+ added tests for parse_search_terms()
* updated build system
+ implemented search_free()
* updated build system
* renamed function: parse_search_terms -> search_parse_terms
* fix build warnings
* moved messages from search.c into msg.h
* rename sql file for db creation
+ added comment
- drop strings_idx (considered to use FTS in database)
* update search description
* changes in search_t:
    1) use flags instead single bool value
    2) renamed members of struct for single style
+ db version check