ExtensionHistory.historyIdToRef should be cleared when changing session

[GoogleCodeExporter]

Steps to reproduce the issue:
1. Run ZAP;
2. Spider a (big) site (to create a lot of page entries);
3. Check the instance variable ExtensionHistory.historyIdToRef (example: using 
VisualVM);
4. Create a new session;
5. Check again the instance variable ExtensionHistory.historyIdToRef and note 
that it has the same contents when it shouldn't;

Remarks:
This may lead to an OutOfMemoryError (it keeps references to 
HistoryReference(s) which itself may keep references to Alert(s) and 
SiteNode(s)) and the following exception(s):
[...]
1010313 [ZAP-PassiveScanner] ERROR 
org.zaproxy.zap.extension.pscan.PassiveScanThread  - Failed on record 337 from 
History table
org.parosproxy.paros.network.HttpMalformedHeaderException: No history reference 
for id 337 type=2
    at org.parosproxy.paros.model.HistoryReference.getHttpMessage(Unknown Source)
    at org.zaproxy.zap.extension.pscan.PassiveScanThread.run(Unknown Source)
1010313 [ZAP-PassiveScanner] ERROR 
org.zaproxy.zap.extension.pscan.PassiveScanThread  - Failed on record 338 from 
History table
org.parosproxy.paros.network.HttpMalformedHeaderException: No history reference 
for id 338 type=2
    at org.parosproxy.paros.model.HistoryReference.getHttpMessage(Unknown Source)
    at org.zaproxy.zap.extension.pscan.PassiveScanThread.run(Unknown Source)
[...]

ZAP Version:
Version 2.0.0 (and trunk r3020).

Original issue reported on code.google.com by THC...@gmail.com on 8 Apr 2013 at 3:57

[GoogleCodeExporter]

r3048

Original comment by THC...@gmail.com on 14 Apr 2013 at 6:37

• Changed state: Committed

[GoogleCodeExporter]

Original comment by psii...@gmail.com on 15 Apr 2013 at 8:42

• Added labels: Build-20130415

[GoogleCodeExporter]

Fixed in 2.1.0

Original comment by psii...@gmail.com on 18 Apr 2013 at 9:49

• Changed state: Fixed