alter_syntax: more parameters

[kysko]

A feature enhancement suggestion:

When changing or extending the markdown syntax with the help of alter_syntax, one might need parse_blocks in addition to the syntax parameter.

A simple change in a line does it:

syntax = options.alter_syntax(syntax, parse_blocks)

Although it's easy to pass writer to the new parser, one might even go further with the following, for convenience:

syntax = options.alter_syntax(syntax, parse_blocks, writer)

I've successfully used this second version in a personal project.

However, I don't have the "whole picture" like you people, so don't know if the above would break something somewhere I haven't looked.

[tarleb]

I second this, having parse_blocks and parse_inlines as additional parameters would be very helpful.