files of task2 modified
added files of task3
modified shell files added
Revert "modified shell files added"

This reverts commit 2ec78cd38fc1a99fe8b084086d678f60c748896c.
newshell files added
Revert "newshell files added"

This reverts commit d81b907b9ef900e437bc3c0cfeb4e6d3400dd5c3.
modified shell files added
modified shell files added2
some codestyle changes
debug outputs deleted
batch mode fixed, Exit strategy added
trycatch to Casting
moved Database files to database package
Shell.terminate() changed
some trycatchs fixed
Exceptions fixed
Corrections after Andrey and Radim's review
Fixed bug if db directory cointains non-directory files,
Added AbstractTableCommand to avoid code duplication.
protectect load -> private load
changed put strategy