RawParam not escaped properly

**Type of issue**: bug report

**Impact**: no functional change

**Development Phase**: request

**Other information**

**If the current behavior is a bug, please provide the steps to reproduce the problem:**

**What is the current behavior?**
```scala
class SB_IO(pinType: String) extends ExtModule(Map(
"PIN_TYPE" -> RawParam("6'b0110_01"),
...
```

produces this FIR file:

```
extmodule SB_IO :
output PACKAGE_PIN : Analog<1>
...

defname = SB_IO
parameter PIN_TYPE = '6'b0110_01'
parameter PULLUP = 0
...
```

and FIRRTL crashes with:

```
[info] Running org.calsol.databucket.Top
[info] [0.003] Elaborating design...
[info] [1.000] Done elaborating.
line 1508:36 token recognition error at: ''\n'
line 1508:28 mismatched input 'b0110_01' expecting NEWLINE
line 1522:36 token recognition error at: ''\n'
line 1522:28 mismatched input 'b1001_00' expecting NEWLINE
line 1536:36 token recognition error at: ''\n'
line 1536:28 mismatched input 'b0000_01' expecting NEWLINE
line 1550:36 token recognition error at: ''\n'
line 1550:28 mismatched input 'b0000_01' expecting NEWLINE
line 1564:36 token recognition error at: ''\n'
line 1564:28 mismatched input 'b0000_01' expecting NEWLINE
[error] (run-main-2c) firrtl.SyntaxErrorsException: 5 syntax error(s) detected
firrtl.SyntaxErrorsException: 5 syntax error(s) detected
at firrtl.Parser$$anonfun$1.apply(Parser.scala:43)
at firrtl.Parser$$anonfun$1.apply(Parser.scala:27)
at firrtl.Utils$.time(Utils.scala:182)
at firrtl.Parser$.parse(Parser.scala:27)
at firrtl.Driver$$anonfun$getCircuit$1$$anonfun$apply$3.apply(Driver.scala:194)
at firrtl.Driver$$anonfun$getCircuit$1$$anonfun$apply$3.apply(Driver.scala:171)
at scala.Option.getOrElse(Option.scala:121)
at firrtl.Driver$$anonfun$getCircuit$1.apply(Driver.scala:171)
at firrtl.Driver$$anonfun$getCircuit$1.apply(Driver.scala:160)
at scala.util.Try$.apply(Try.scala:192)
at firrtl.Driver$.getCircuit(Driver.scala:160)
at firrtl.Driver$$anonfun$execute$1.apply(Driver.scala:213)
at firrtl.Driver$$anonfun$execute$1.apply(Driver.scala:210)
at logger.Logger$$anonfun$makeScope$1.apply(Logger.scala:129)
at scala.util.DynamicVariable.withValue(DynamicVariable.scala:58)
at logger.Logger$.makeScope(Logger.scala:127)
at firrtl.Driver$.execute(Driver.scala:210)
at chisel3.Driver$.execute(Driver.scala:182)
at chisel3.Driver$.execute(Driver.scala:202)
at org.calsol.databucket.Top$.main(main.scala:306)
at org.calsol.databucket.Top.main(main.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
```

Also, the Lattice toolchain (iCEcube2) inexplicably treats
```
SB_IO #(.PIN_TYPE(6'b0110_01), ...
```

differently from

```
SB_IO #(.PIN_TYPE(25), ...
```

so IntParam doesn't work. But surprisingly, Yosys does do the right thing...

**What is the expected behavior?**

RawParam doesn't crash FIRRTL

**Please tell us about your environment:**

chisel3 (testers2) / firrtl / treadle latest master

**What is the use case for changing the behavior?**

giving me FPGA IOs that actually work as IOs

🔥
🗑️