Plain text mode besides (X)HTML mode

[dahlia]

Seonbi currently provides two modes for input/output formatting:

• HTML
• XHTML

However, sometimes we need to apply adjustments on text before it's compiled to HTML, or it won't be compiled to HTML at all. For such demands, it's good to have one more mode: plain text.

Fortunately, it apparently is not that difficult to implement:

1. Escape the whole input to HTML character entities (or simply put it to a CDATA section).
2. Make adjustments on it.
3. Unescape the whole output.

[dahlia]

Now the Boolean option xhtml is replaced by the new option contentType, which should be one of text/html and application/xhtml+xml. Two tasks to do remain:

• Add text/plain type.
• Add text/markdown type.
• Rename sourceHtml & resultHtml fields to content in HTTP API. /cc @channprj @moreal

[dahlia]

Now we have 4 modes:

[channprj]

Thank you 👍🏼