CMake Find Module and UseFile for ODB.

### Windows ODB installation notes:
Install all odb components into some directory and setup environment variable CMAKE_PREFIX_PATH=your_odb_installation_directory. 
Directory must contain sub-directories bin for executables(especially odb.exe) and dlls, 
include/odb for odb headers and lib for lib files. 
For example c:\odb\bin, c\odb\include and c:\odb\lib. Note: when you copy odb.exe - do not copy only exe file - you need all directories from archive.

### Generate project Windows/Linux
* One structure per file. Simply run cmake without options.
* All persistent structures in one file - set option AT_ONCE=ON. For example cmake . -DAT_ONCE=ON