Silp

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Remove blessings usage under windows, can work under windows now (only test with git windows' bash)

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Put the `.silp_backup` and `.silp_test` folders under `~`, otherwise they may became garbage in project folder

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Make sure there is at least one space before the suffix
use " --SILP:" for sql

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Add SQL to language list

- Use "/*__SILP__*/" for the generated tag, since in MySql if using
"--__SILP__", then if there is one line without space there is a
corner case that there is no space before it.
https://dev.mysql.com/doc/refman/5.1/en/ansi-diff-comments.html

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Use "%" instead of "%%" in erlang language

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Add simple plugin support for more complex macro.

- Currently plugins should be put under project's silp_plugins
(Project means the folder holding silp_xx.md)
- plugin macro has format as module:func(param1, param2, ...)
module here is the name of the python plugin, func is the name of
function
- also expose silp.error/info/verbose, then the plugin codes can print
debug information with them.

Add support for Erlang (both erl, and hrl)