template: add `while' construct

adjust my copyright email address this code is now part of Game of Trees too!

template: add quoting support inside {{ ... }} blocks

template: add -o to specify the output file This way template can delete output file on parsing errors, which helps a lot with make(1).

fix parsing of {! !} block after content the '{' and '!' characters were pushed back in the wrong order and so read as "!{" instead of "{!". add regress for this case, and for similar usage (02 change.)

template: add for loops

u_char -> unsigned char for portability

template: some printf -> puts conversions

template: allow '|' in some contexts

template: fix possible use-after-free and drop the `render' sugar if some of the tp_* function fails, the inner code could free the template too (that's what galileo does), so `tp->tp_ret' would access free'd memory! Instead, add a local variable `tp_ret' to keep track of the return code. While here, drop the `render' shortand that adds the argument call, the template_reset function and adapt the regress.

template: preserve \

template: add `printf' support

template: drop `| escape': it's the default

template: don't spam `#lines's

be portable: switch to a custom version of Kristaps' oconfigure