add-ons, initial implementation
introducing add-on features
some further progress on add-on features
a very basic implementation of sql templates
report the error, when initializing an add-on failed
sql templates, functional
example template
return a list of missing values, if any
salt functions moved to a separate file
a little re-org of the require()s
add-on's sqlt property is an object of SQL templates
code formatting (wrapping long lines)
check for add-on's features and sqlt before using
only call add-on's setup method, if it is defined
minor code formatting
comments on sqlt
catching exceptions that fs.statSync() may cause
merge master into feature-addons
log sql before and after transformations
remove unneeded checks