add support for path conversions

[anb0s]

E.g. for Git-Shell under Windows path conversion for calling command or copy path actions should be possible.

[anb0s]

Added predefined "converters" as second argumend for easyshell variables:
unix, windows, lf, crlf, slash, backslash

e.g.:
${easyshell:line_separator:unix} or ${easyshell:line_separator:lf} --> will return LF also on Windows
${easyshell:line_separator:windows} or ${easyshell:line_separator:crlf} --> will return CRLF also on Unix (Linux, Mac OS X etc.)
${easyshell:resource_loc:unix} or ${easyshell:resource_loc:slash} --> will convert path with Unix slashes on Windows, e.g.: D:/programm/my_prog/test.cpp

[anb0s]

first part is done for RC1 #80, more to come with #85