fix: correct isValueUntyped() to handle typed constants

fix: struct type detection, collision between field and type name

fix: detect non boolean condition for IF and FOR statements

interp: fix array size assignment type inference

fix: handle type declaration inside function

chore: allow to build tags

fix: shift operator inherits its type from first arg only

chore: revert stdlib improvements

fix: exclude syslog for windows, nacl, and plan9.

feat: support yaegi in go playground