Add string.c to CMakeList.txt
Add basic ws_value_string implementation
Add method stubs to string.c

Conflicts:
	src/values/string.c

Conflicts:
	src/values/string.c
Add implementation of ws_value_string_init()
Add implementation for ws_value_string_new()
Add implementation for ws_value_string_get_str()
Add implementation for ws_value_string_set_str()
Add implementation for value_string_deinit()
Merge pull request #168 from xVin/add-string_value_type

Add string value type
Add preliminary definition of the processor type
Add files for command interface datatypes
Add datatypes for command arguments
Add datatype for commands
Add datatype for statements