Review comptime options

[batiati]

There are a lot of comptime options, some of them still not implemented, poorly named, or not so obvious.
Some options could be visible internally only.

Example:

pub const Features = struct {
    allow_redefining_delimiters: bool = true,
    preseve_line_breaks_and_indentation: bool = true,
    lambdas: Lambdas = .{ .enabled = .{} },
};

Here we can keep track of all comptime options, and the current status:

Option	Meaning	Status
ParseTextOptions.copy_strings	Parsed templates should dupe all strings or just take slices from the template source	Implemented
ParseFileOptions.read_buffer_size	Buffer size of the streamed parser.	Implemented, but it could have a better name
Features.allow_redefining_delimiters	Allows redefining the delimiters through the tags '{{=' and '=}}'	Not implemented
Features.preseve_line_breaks_and_indentation	Follow strict mustache's rules about blank spaces and indentation	Implemented, but it could have a better name
Lambdas.disabled	Disable lambdas support, which means, there is no need to store the tag's content	Implemented
Lambdas..enabled.max_recursion	When enabled, prevents recursive lambda expansion	Not implemented
ContextMisses.empty or fail	Behaviour when interpolating an unknown variable	Not implemented, defaults to "empty" always