Enhanced handling of \ character in run, py, r, vision steps

[kensoh]

Follow-up from #200 - the character would be treated as escape character now. It should ideally be handled as a backslash and be passed on to the target integration. See if there is a way to implement this and still preserve backward compatibility. Because some users may have used '\\' in order to send '\'. If blindly replace very '\' with '\\' it can make their scripts break or work in a way that's not intended.

[kensoh]

below looks like need to convert '\' to '\\'

• run
• r
• py
• vision

[kensoh]

@Aussiroth @lohvht - solution found. The commit 297f37d breaks backward compatibility to move to stable state standard. [END_OF_LINE] token is used during buffering phase in order not to replace incorrectly during parsing. The backward compatibility broken for example -

py open('c:\\\\nest\\\\file.txt','w') in existing scripts can be used to open a file. but supporting this will mean py open('c:\\nest\\file.txt','w') becomes py open('c:\nest\file.txt','w') which is breaking the future stable state where what is sent is what is received by python.