allow pipe syntax
ensure to correctly terminate hex string with non-hex char(';')
Merge pull request #167 from KeenS/hotfix

fix a bug of `string-copy!` with same dist and src
remove sLETREC_SYNTAX
remove rLETREC_SYNTAX
remove custom target `no-act'
fix r7rs-tests. rational literal is not required to generate an exact value
all float numbers can be considered inexact rational numbers
update travis config
remove redundant brace following review
add error check
follow completely @wasabiz's code
Merge pull request #168 from KeenS/pipe-reader

allow pipe syntax
`(rational? +inf.0)` should be #f