README: typo
rename Decimal => Double

for consistency, to avoid further confusion.
Renamed to: PN_TDOUBLE, PNDouble, PN_IS_DOUBLE
bump ChangeLog
Rename potion_decimal to potion_double

but this is still inconsistent. potion_double should be the initializer, not
potion_real.
Rename potion_double to potion_strtod, potion_real to potion_double

potion_double is now the type initializer. Now we have almost consistent type names
Rename PN_IS_NUM to PN_IS_INT
PN_FNUMBER=>PN_FINTEGER, add seperate int+dbl methods

IS_NUM is a misnomer. Number is Integer or Double.
Provide seperate methods for future specialized _ii and _dd ops,
esp. with the upcoming type inferencer or typed variables
intdbl: initialize int+dbl vtables, add I+D sig types

int+dbl vtables derive now from number, not obj.
Still a couple of problems
Fix all tests: a literal int is still just a Number,

not an Integer. It is easier that way still. The type inferencer or
excplicity types will make them Integer then. Ditto for step, times, to.

Add a number? method.
PN_IS_DBL: also check for new vtable TDOUBLE (not yet used)
assign: document plan in core/compile.c AST_ASSIGN lhs EXPR
assign: generaic ast walker and walk_msg callback

for now only:
  detect msg in rhs of assign to check if compile-time matching
  can be done. else defer to runtime matching, resp. sequential assignment.
assign: add quoted msg test, see returned bindings
assign: fix walker, add equal cmp with lhs value (WIP)

replace 1 = x with 1 equal x. not constant folding yet for such binops.
need to add a EQUAL op, which is better than CMP: for all objects check cmp == 0.
assign: add EQUAL op, compare any value, not just numbers

also added potion_table_equal, potion_tuple_equal, potion_any_equal, potion_table_cmp
assign: add testcases (no compile-time match yet)