Fix duplicated account parsing

[febo]

Problem

PR #176 refactored the entrypoint and inlined the processing of accounts, but the parsing of duplicated accounts is wrongly storing the address to an AccountInfo instead of an Account.

Solution

Dereference the AccountInfo to store the address of its Account. The PR also includes a test for duplicated account parsing.

As a side-effect of the fix, CU consumption improved:

Name	CUs	Delta from current
Account (0)	9	--
Account (1)	13	--
Account (2)	13	-8
Account (3)	33	-1
Account (4)	41	-1
Account (5)	48	-1
Account (6)	63	-1
Account (7)	67	-1
Account (8)	74	-1
Account (16)	139	-1
Account (32)	257	-1
Account (64)	500	-1

cc: @cavemanloverboy

Fixes #208

[joncinque]

Ah too bad this snuck in, but looks good to me! I feel silly because I almost asked for a test with duplicates in the previous PR.

[febo]

Ah too bad this snuck in, but looks good to me! I feel silly because I almost asked for a test with duplicates in the previous PR.

I feel the same. There was not a good reason not to include one.

[joncinque]

Looks great, thanks!