Improve naming of macros in lexer.
Move js_ValueType into jsrun.h
Auto-generate list of operator names.
Improve opcode naming.
Use special TCALL opcode for foo.bar() calls that set 'this' for the call.
Compile logical or/and operators with early termination.

Make the && and || operators right-associative since that generates
better code, and should make no difference in semantics.