eth/tracers/logger: improve markdown logger

[holiman]

This PR improves the output of the markdown logger a bit.

• Remove RStack field,
• Move Stack last, since it may have very large vertical expansion
• Make the pre- and post-exec metadata structured into a bullet-list

using the command go run ./cmd/evm/ --json --code 604019 run, with a hack to enable the markdown-output, here is the before (current master) and after (this PR).

Before

From: 0x000000000000000000000000000073656E646572
To: 0x0000000000000000000000007265636569766572
Data: ``
Gas: 10000000000
Value `0` wei

Pc	Op	Cost	Stack	RStack	Refund
0	PUSH1	3	[]	0
2	NOT	3	[0x40]	0
3	STOP	0	[0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffbf]	0

Output: ``
Consumed gas: 6
Error: ``

After

Pre-execution info:

• from: 0x000000000000000000000000000073656E646572
• to: 0x0000000000000000000000007265636569766572
• data: ``
• gas: 10000000000
• value: 0 wei

Pc	Op	Cost	Refund	Stack
0	PUSH1	3	0	[]
2	NOT	3	0	[0x40]
3	STOP	0	0	[0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffbf]

Post-execution info:

• output: ``
• consumed gas: 6
• error: <nil>

[s1na]

LGTM