Keep going when there is conversion error.

[xuehuichao]

Right now the script may quit during conversion errors. For example:

INFO: MainThread Exiting freemindlatex ...
Traceback (most recent call last):
  File "/usr/local/google/home/xuehuichao/.local/bin/freemindlatex", line 11, in <module>
    sys.exit(main())
  File "/usr/local/google/home/xuehuichao/.local/lib/python2.7/site-packages/freemindlatex/__main__.py", line 377, in main
    RunEditingEnvironment(cwd)
  File "/usr/local/google/home/xuehuichao/.local/lib/python2.7/site-packages/freemindlatex/__main__.py", line 345, in RunEditingEnvironment
    CompileDir(directory)
  File "/usr/local/google/home/xuehuichao/.local/lib/python2.7/site-packages/freemindlatex/__main__.py", line 259, in CompileDir
    result = _CompileInWorkingDirectory(work_dir)
  File "/usr/local/google/home/xuehuichao/.local/lib/python2.7/site-packages/freemindlatex/__main__.py", line 208, in _CompileInWorkingDirectory
    'utf8').read())
  File "/usr/local/google/home/xuehuichao/.local/lib/python2.7/site-packages/freemindlatex/convert.py", line 345, in __init__
    dom = minidom.parseString(mm_file_content)
  File "/usr/lib/python2.7/xml/dom/minidom.py", line 1928, in parseString
    return expatbuilder.parseString(string)
  File "/usr/lib/python2.7/xml/dom/expatbuilder.py", line 940, in parseString
    return builder.parseString(string)
  File "/usr/lib/python2.7/xml/dom/expatbuilder.py", line 223, in parseString
    parser.Parse(string, True)
xml.parsers.expat.ExpatError: no element found: line 1, column 0

In this case, evince will quit. We should keep going in this case, and possibly produce errors to the compiled pages.

[xuehuichao]

The conversion error may come from a race condition: freemind writes to the file while we haven't finished the last conversion.

[xuehuichao]

It is actually because I tried reading files when they are not ready. It is too often that when I hit save, and the program tries to read the file at the same time.

I currently check mtime. mtime changes when the file is open for write, before it's closed. When the writes (e.g. to .mm) takes more than a couple of ms, there is a high chance that my read happens before the write is finished. I currently added a "sleep" statement to avoid this.