better explanation of current MSSQL support
cross ref to orderby syntax
debugging tips for PyCharm
Replaced relative URLs in ajax() examples

Using relative URLs in the `ajax()` call examples leads to confusion because in many cases they don't work. All examples were changed to use the `URL()` function, which always generates the proper URL.
{{=URL instead of {{URL
changing typo 'lamba' to 'lambda' (line 2596)

"links = [dict(header='Virtual Field 1',body=lamba row:row.vfield),...] )" changed to "links = [dict(header='Virtual Field 1',body=lambda row:row.vfield),...] )"
Merge pull request #239 from niphlod/fix/chapter06

better explanation of current MSSQL support
Merge pull request #240 from timrichardson/tr20141030

cross ref to orderby syntax
Merge pull request #241 from timrichardson/pycharm_tips

debugging tips for PyCharm
Merge pull request #242 from spokes8249/patch-1

changing typo 'lamba' to 'lambda' (line 2596 in chapter 7)