Escaped interpolation symbols in "..." generate incorrect python code

[snoopyjc]

Escaped interpolation symbols in "..." generate incorrect python code. Also, symbols { and } need to be escaped (by doubling them) in python f"..." strings. For example:

print "three=i\@{3}\$\n";
print "three=i{3}$i\n";

Generates:

print(f"three=i\@{3}\$")
print(f"three=i{3}{i}")

Instead of:

print("three=i@{3}$")
print(f"three=i{{3}}{i}")

[snoopyjc]

Fixed in https://github.com/snoopyjc/pythonizer