partial 1.8 xml support - simple, external check keys

we support 1.8 xml, but we do it partially only. in 2.0, some item key syntax changed, but when importing 1.8 xml, we do not do it properly - we

• fail on simple checks
• import broken external check keys

for simple checks, we should transform them;
for external checks, we should a) add {HOST.CONN} as the first macro in the item key and replace spaces between arguments with commas