#1145 freemind does not close files after export

[Ron Smits]

When exporting to for example odt or html, Freemind does not close the file properly. Opening the file while freemind is still running will result in "file is still open by java" message (roughly translated from dutch)

System: windows 7 X64
Java version 1.7

Reproduce:
1) open freemind
2) load a map(or make one)
3) export to openoffice writer document
4) open the document BUT keep freemind running
5) observe the "opened by java" warning, file can only be opened read only

alternative reproduce:
4) delete the document while freemind is running
5) observe error dialog reporting file opened by java

[Christian Foltin]

Fixed in git.