Parse decimal values

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add 'Variables' command.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Move 'slow' test files to different subdir. Modify CTestCustom.cmake.in to run leantests.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>