[Bug-apl] Complex minus float gives wrong result

[Kevin Anderson]

Subtract with a complex on the left and a float on the right acts as if the 
operands were swapped:

2J8 - 3.0
1J¯8
3.0 - 2J8
1J¯8

However, complex minus int or int minus complex is OK:
2J8 - 3
¯1J8
3 - 2J8
1J¯8

FloatCell.cc::bif_subtract is executing "return A->bif_subtract(Z, this)" when 
A is not a real, no doubt inspired by the pattern used in FloatCell::bif_add. 
It should rather take its inspiration from IntCell::subtract and do 
"bif_negative(Z); return A->bif_add(Z,Z);" instead.

[Bug-apl] UserFunction_header::remove_duplicate_local_var

[Kevin Anderson]

Suggest:
while(pos < local_vars.size(); ++pos) {if (sym == local_vars[pos]) 
{local_vars[pos] = local_vars.back();
local_vars.pop_back();}}instead of:

for (; pos < local_vars.size(); ++pos) {if (sym == local_vars[pos]) 
{local_vars[pos] = local_vars.back();
local_vars.pop_back();}}

[Bug-apl] UserFunction_header::remove_duplicate_local_var

[Kevin Anderson]

Sorry about that last; accidentally sent in mid-compose!  Here's how it should 
have read.

In remove_duplicate_local_var,

Suggest:
while (pos < local_vars.size(); ++pos) {if (sym == local_vars[pos]) 
{local_vars[pos] = local_vars.back();
local_vars.pop_back();} else++pos}instead of:

for (; pos < local_vars.size(); ++pos) {if (sym == local_vars[pos]) 
{local_vars[pos] = local_vars.back();   //[KA] 
Probable bug here  //[KA] local_vars[pos] still duplicates 
sym   //[KA] if local_vars.back() also == sym
local_vars.pop_back();}}Two examples of headers which should elicit 
the issue:

FUN;LV;LV;LV
FUN B;LV;B;B