Added a few test cases
Added defines for the start and end chars of tags
Added tag_handle functions
text_escape expects a const char
Added some debug printfs
is_tag will now get all of the tag and if valid will pass it to the
tag_handle function
Created tag_info struct which will passed to the tag_handle_* functions
The code will now handle tag variables and tag escaped

Added tag_clean that, for now, just removes the first char. This will be
changed to handle more cases like empty space and check if the first
char is one that tells which tag type the tag is
Added defines with default start and end chars for tag