Builder: Fix max_length in existing table

- Fixed handling of max_length when driver retrieves null values for
field data in existing table by defaulting to an empty string instead of
1, allowing form validation to alert the user to issues rather than
silently passing with bad values
- Improved/fixed error messages on modulebuilder_form
- Rearranged controller and fixed some potential issues when checking
for the public controller
Builder: Checkboxes to replace true/false select

- Replace true/false select fields with checkboxes
- Exclude log user fields from public index
- Add validation for log user fields
- Reducing the number of calls to input->post() in views and the
modulebuilder library
- Refactoring modulebuilder library to pack method arguments into an
array to reduce the need to pass multiple arguments (and change the
argument list or call input->post() every time fields are added to the
form)
Builder: Fix #769 Filter out soft-deleted records

Filtered out soft deleted records on public index
Builder: consolidate handling of database types

- Reduced duplication of database-type-related information throughout
module builder.
- Database type information should always be pulled from the
modulebuilder library, which attempts to pull the information from the
modulebuilder config file (which should allow for use with databases
other than MySQL)
Builder: Fix error building real number fields

As noted by @boblennes
https://github.com/ci-bonfire/Bonfire/commit/df8388779019cd6f891f00d10fb138a35d900fe5#commitcomment-5607888