Ibase result

[mlazdans]

Sorry for large (again) pull request, it just happened 😬 Please test it thoroughly first.

Address issues:

• Vulnerability in Firebird PHP driver #75
• Make tests/long_names_001.phpt pass #79
• Why separate struct - ibase_result? #80
• Redundant aliases checks in _php_ibase_fetch_hash() #81
• Passing result from ibase_query() to ibase_num_params() causes segfault. #84
• ibase_param_info() / ibase_field_info() prints garbage with table names, field names > 31 chars #87

Some other changes:

• Removed structs: ibase_result, ibase_statement and associated PHP resource types
• Precompute HashTable structures for ibase_fetch_() instead on each call
• Remove in_sqlda, out_sqlda double allocations
• Allocate NULL indication buffer per query instead per field
• Some code deduplication
• Introduce versioning and expose IBASE_VER constant, starting from 6.1.1

Backwards incomptible (kinda) changes:

• Broke the "test execute procedure" part of tests/006.phpt when ibase_execute($query) is used after ibase_free_query($query). This is improper use anyway and only worked by accident due to how single returns from a procedure are handled. To illustrate this I added tests/use_after_free-001.phpt and tests/use_after_free-002.phpt.