- Several details in 'lcode.c'
- A few more tests for code generation
- Bug in assert in 'lcode.c' ("=" x "==")
- Comments in 'lopcodes.h' and 'ltable.c'

Function names in the API use only lowercase letters.

The difference in performance between immediate operands and K operands
does not seem to justify all those extra opcodes. We only keep OP_ADDI,
due to its ubiquity and because the difference is a little more relevant.
(Later, OP_SUBI will be implemented by OP_ADDI, negating the constant.)

Plus, this commit removes useless 'tm' parameters in 'op_*' macros.

In arithmetic/bitwise operators, the call to metamethods is made
in a separate opcode following the main one. (The main
opcode skips this next one when the operation succeeds.) This
change reduces slightly the size of the binary and the complexity
of the arithmetic/bitwise opcodes. It also simplfies the treatment
of errors and yeld/resume in these operations, as there are much
fewer cases to consider. (Only OP_MMBIN/OP_MMBINI/OP_MMBINK,
instead of all variants of all arithmetic/bitwise operators.)

A metamethod call like '1 << a' was not being properly resumed
if it got yielded.

The family of opcodes OP_ADDK (arithmetic operators with K constant)
were not being handled in 'luaV_finishOp', which completes their
task after an yield.

Warnings are mostly a tool to help developers (e.g., by showing hidden
error messages); regular users usually don't need to see them.