Improve --initplugin

[ThomasTJdev]

plugin.nim:

• Include required imports: ´import db_sqlite`
• Include nimf file: include "html.nimf"

Folder structure:

• Create plugin plugins folder instead of tmp

Generel:

• Plugin name is made to lowercase. Keep user defined chars when inserting them into plugin.json etc.

html.nimf:

• Make a template example to get user started. It's very important to show the user, that an * is required due to the plugin structure.