Ibase result

[mlazdans]

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

Address issues:

• #75
• #79
• #80
• #81
• #84
• #87
• #89

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.

[mlazdans]

Added Windows binaries: https://github.com/FirebirdSQL/php-firebird/releases/tag/v6.1.1-RC.0

[mlazdans]

Any feedback? I will merge then 😅