Multiline classdesc crashing global index

[ambischof]

Multiline classdesc are not escaped properly and everything after the first linebreak renders after the table.
consider:

/**
 * @class foo
 * @classdesc this is a single line classdesc
 */

/**
 * @class Bar
 * @classdesc
 * this is a
 * multiline
 * class description
 */

/**
 * @class Bizz
 * @classdesc this is a casualty
 */

output:

## Classes
Global | Description
------ | -----------
foo | this is a single line classdesc
Bar | this is a
multiline
class description
Bizz | this is a casualty

## foo
this is a single line classdesc

**Kind**: global class  
## Bar
this is a
multiline
class description

**Kind**: global class  
## Bizz
this is a casualty

**Kind**: global class 

result:

Classes

Global	Description
foo	this is a single line classdesc
Bar	this is a

multiline
class description
Bizz | this is a casualty

foo

this is a single line classdesc

Kind: global class

Bar

this is a
multiline
class description

Kind: global class

Bizz

this is a casualty

Kind: global class

---

Apart from this issue, I also suggest that if there is a classdesc AND a summary, that the summary is used for the global index instead, since classdesc, like description, may be very long.

[ambischof]

For what it's worth, I got around it in a fork I made here https://github.com/ambischof/dmd-bitbucket (see change).

I just made it use the summary instead of the classdesc if one was available. (Another workaround would have been just cutting off after the first line but that would have involved helpers and seemed like too much work)