This adds a second variant for the existing "attribute" function.
The current function requires both a target feature and attribute
name to be specified, while the NEW variant just uses the current
feature.
E.g.
NEW:
attribute( 'name' ) -> returns the value stored in 'name' attribute
for the current feature
EXISTING:
attribute( @atlas_feature, 'name' ) -> returns value stored in 'name'
attribute for the current atlas feature
It's just a faster shorthand version!
A new script then parses these json help files into the html help
contents, in a standardised manner. Previously, the function help
was a bunch of different formats and structures.
Now, a custom stylesheet can be applied (and later tweaked!) to
format these help. Eg, this commit colors variables and function
names in the syntax section for greater readability.
