Issue #39 fix

It seems, issue #39 is fixed. This issue was caused by following. `makeModelString` in `qucslib_common.h` cannot process  DefaultSymbol section of the library file properly. Now `bool default_sym` parameter is added. By default it is set to `false`. If we want to process DefautSymbol instead of Symbol it's need to set it into `true`.

With this fix components are now placed in schematic correctly.

Also added `-Wall` compiler option for `cmake` build system.