Enhancement: Add Automatic Token Standard Detection Printer

## Summary
Add a printer that automatically identifies and classifies token contracts (ERC-20, ERC-721, ERC-1155) based on their implemented interfaces, helping developers and auditors quickly understand the token landscape in a codebase.

## Motivation

Token contracts are fundamental to the blockchain ecosystem, but identifying them in large codebases can be challenging:

1. **Manual identification is error-prone** - Tokens may not follow naming conventions
2. **Partial implementations are common** - Contracts may implement subsets of standards
3. **Multiple token types** - A codebase may contain various token standards
4. **Integration requirements** - External tools need to know which contracts are tokens
5. **Security implications** - Token contracts require specific security considerations

An automatic token detector would:
- Quickly identify all token contracts in a project
- Classify tokens by their standard (ERC-20, ERC-721, etc.)
- Detect partial or non-compliant implementations
- Aid in security reviews and integration planning

## Token Detection Methodology

The printer identifies tokens by checking for standard function signatures and events:

### ERC-20 Detection
- `totalSupply()`, `balanceOf(address)`, `transfer(address,uint256)`
- `allowance(address,address)`, `approve(address,uint256)`, `transferFrom(address,address,uint256)`
- Transfer and Approval events

### ERC-721 Detection
- `balanceOf(address)`, `ownerOf(uint256)`, `safeTransferFrom` variants
- `transferFrom(address,address,uint256)`, `approve(address,uint256)`
- `setApprovalForAll(address,bool)`, `isApprovedForAll(address,address)`
- Transfer, Approval, and ApprovalForAll events

### ERC-1155 Detection
- `safeTransferFrom(address,address,uint256,uint256,bytes)`
- `safeBatchTransferFrom(address,address,uint256[],uint256[],bytes)`
- `balanceOf(address,uint256)`, `balanceOfBatch(address[],uint256[])`
- `setApprovalForAll(address,bool)`, `isApprovedForAll(address,address)`

## Expected Output

```
Token Contract Analysis
=======================

ERC-20 Tokens (3 found):
-------------------------
1. MyToken (contracts/MyToken.sol:10)
Confidence: HIGH (100% interface compliance)
✓ All required functions implemented
✓ All required events implemented

2. PartialToken (contracts/PartialToken.sol:25)
Confidence: MEDIUM (83% interface compliance)
✓ 5/6 required functions implemented
✗ Missing: approve(address,uint256)
✓ All required events implemented

ERC-721 Tokens (2 found):
--------------------------
1. MyNFT (contracts/MyNFT.sol:15)
Confidence: HIGH (100% interface compliance)
✓ All required functions implemented
✓ Includes metadata extension

2. BasicNFT (contracts/BasicNFT.sol:30)
Confidence: HIGH (89% interface compliance)
✓ Core functions implemented
✗ Missing: safeTransferFrom variants

ERC-1155 Tokens (1 found):
---------------------------
1. MultiToken (contracts/MultiToken.sol:20)
Confidence: HIGH (100% interface compliance)
✓ All required functions implemented

Partial/Unknown Implementations (2 found):
-------------------------------------------
1. CustomToken (contracts/CustomToken.sol:40)
Appears to be: Modified ERC-20
Implements: 4/6 ERC-20 functions
Note: May be intentionally non-standard

2. HybridToken (contracts/HybridToken.sol:50)
Appears to be: ERC-20/721 Hybrid
Warning: Implements conflicting interfaces

Summary Statistics:
-------------------
Total contracts analyzed: 45
Token contracts found: 8
- ERC-20: 3 (2 fully compliant, 1 partial)
- ERC-721: 2 (2 fully compliant)
- ERC-1155: 1 (1 fully compliant)
- Non-standard: 2
```

## Advanced Features

### Extension Detection
- Identify common extensions (Mintable, Burnable, Pausable for ERC-20)
- Detect metadata and enumerable extensions for ERC-721
- Flag non-standard modifications

### Compliance Checking
- Verify function signatures match standards
- Check return types and modifiers
- Validate event parameters

### Security Warnings
- Flag missing overflow protection in ERC-20
- Detect external calls in transfer functions
- Identify reentrancy risks

## Command-Line Interface

```bash
# Basic usage
slither . --print token-detector

# With options
slither . --print token-detector \
--token-threshold 0.8 \ # Min implementation % to classify
--include-interfaces \ # Include interface contracts
--check-extensions \ # Detect token extensions
--export-json tokens.json # Export results to JSON
```

## Benefits

1. **Quick project overview** - Instantly understand token landscape
2. **Integration planning** - Know which contracts to integrate with
3. **Security focus** - Prioritize token contracts for review
4. **Compliance verification** - Ensure standard compliance
5. **Documentation aid** - Auto-generate token documentation

## Priority

**Medium** - This printer provides immediate value for projects dealing with tokens, which represents a large percentage of smart contract development. It aids in documentation, security reviews, and integration efforts. The implementation is straightforward with high accuracy and clear benefits.