Bug: Strings consisting of digits only and starting with 0 are saved without leading zeros

[technicalguru]

Symptom: a value like '036876' that shall be saved as string in database is saved as '36876' (leading zero stripped off).

Reason: TgDatabase\Database class method prepareValue() decides on is_numeric() only whether the value needs quoting or not. Leading zeros are stripped of then when saving to database because the quotes are missing.

[technicalguru]

Solution: use combination of is_numeric() and is_string() to decide on quoting.