Use default parameters for transaction settings from .ini file

[MartinKoeditz]

Based on the pull request from safhome, we should read default transaction settings from php.ini (extension ini).

Default "wait" flag is unusable in real web apps because of many parallel requests. Trying to serialize it with "wait" transactions results in fatal performance degradation. Considering that we haven't settings for default transaction's flags, current defaults make unusable almost all existing CMS with Firebird. With this change we successfully use Joomla! versions from 3.1 upto 3.9 for last 5 years with Firebird as main database for it. #3