Check on leading "[" removed as this check makes it very difficult to…

[ancpru]

… implement custom tags which might want to allow or require this character in the tag body.

A leading square bracket might not be necessary for standard tags, but StandardTagFactory allows registering or overriding of tag implementations which might want to accept this character right after the tag.

[mvriel]

Do you have a use-case where such behaviour is desired? Without a concrete use-case I prefer to stick to the status quo as removing it may have inadvertent side effects

[jaapio]

Thanks for your contribution. We had a better look at this issue and provided a suitable fix that works in more cases as intended.

This issue has been fixed in #200