Add initial files for Firebird engine

Adapted mostly from the MySQL engine
Fix SQL schema for Firebird

Remove NOT NULL from uri
Change VARCHARS from 512 to 255 like in MySQL schema
Quote timestamp
Firebird use FIRST/SKIP instead of LIMIT/OFFSET
Fixes and changes to the Firebird engine

Add param to DBI conection command
Add params to isql
No date_format function in Fb replace with a custom one :)
Add code to create sqitch_db database
Fix command to execute SQL from file
Ad _dt sub
Replace REGEXP op with SIMILAR TO :( not fully compatible
Add all subs from DBIEngine.pm that use LIMIT/OFFSET
Fix the lenght of VARCHAR for the project field in the tags and events tables
Test 'live database': Looks like you failed 2 tests of 338 :)

Avoid "Data type unknown" with explicit CAST in log_new_tags sub
Experiment with SIMILAR TO as replacement for REGEXP operator
Fix engine_err_regex and the related test

Looks like you failed 1 test of 338. :D
Fix for _ts2char_format return seconds:60
Fix typo in firebird.t
Replace isql with isql-fb as used by Debian
Add Firebird engine
Fix database name

Fix config tests
Fix database name in different contexts
Add Firebird templates
Fix for drop test database code
Add module to locate isql
Refactor and fix locate_firebird_ms
Add .al to .gitignore
Integrate Firebird utils into the engine module
Make the firebird client a Path::Class::File object