fix Issue #4: wrong file mask handling

(https://github.com/michaellukashov/filecopyex3/issues/4)
fix code style
refactoring: use LENOF instead of constant
refactoring: use :: to indicate global system functions; fix type; fix code style
changelog.txt: update
fix Issue #3: "Scanning directories" dialog is not correctly redrawed

(https://github.com/michaellukashov/filecopyex3/issues/3)
changelog.txt: update
refactoring: flags, attributes, selection indices are unsigned
refactoring: use intptr_t
fix warnings
refactoring: fix code style
bugfix: commands "Copy file under cursor", "Move file under cursor" was not working
changelog.txt: update
FarMenu::SetSelection: improvement
FarPlugin::OpenPlugin: show plugin menu again if menu "Settings..." was selected or if copying is canceled
amend 88714437107fc9abfa7234ad87bc2fbc46a7a4ef
fix code style
fix code style (goto)
refactoring: use :: to indicate global system functions
cleanup