Make more robust dealing with incomplete insts (e.g. during parsing).
Fix icmp rendering - there's a single inst type.
IRRenderer: Allow to output to arbitrary stream.
Add initial version of PLLVMIR parser.

Of course, it accepts only subset of all instructions, but supports
non-SSA programs.
Add roundtrip test for PLLVMIR parser.
Fix regression from previous refactors.
Well, type specified in icmp opcode is argments' type after all.

It's just all arguments must have same type, so it's rendered once.
The type of insrtuction itself is i1 though.
Add print_with_attrs() debugging method.
Add empty line for roundtrip match.