PIXI.Text WordWrap corrections, space detection and correct lines amount

The changes for this pull request are in the commits from Aug 13, 2013:
- "word wrap with space support and lines amount correction"
- "just avoid last empty line on word wrap"

(for src/pixi/text/Text.js)

Changes:
- searchWrapPos does not use a wrap position which is not surrounded by one space character
- lineWrap ignores space characters as first character in a new line
- wordWrap does not add an empty line at the end of a text any longer

You should merge this pull-request first https://github.com/GoodBoyDigital/pixi.js/pull/240 if the changes from here cannot be merged directly.