Revert spurious preprocessor changes introduced in dfa744f
Automatic detrending engine can now handle models written in logs (ref. #309)

 - new command `log_trend_var'
 - new option `log_deflator' to `var' command
Also ignore TeX files produced with options_.TeX = 1
Use syntax log_trend_var(log_growth_factor = …) for consistency
Conditional forecast test: remove spurious changes introduced in dfa744fcb3

As a consequence, reactivate the tests
Mention compatibility with Windows 8
Fix Typo in correlation_mc_analysis
Bugfix in correlation_mc_analysis

Closes #290 and makes #314 obsolete as we store both auto- and
cross-correlations
Merge branch 'master' of https://github.com/DynareTeam/dynare