Cleaned up utils.nim file, more info in description below.

Here is the compiler output/warnings for this part (utils.nim file):

 > private/utils.nim(7, 15) Warning: use Table instead; TTable is deprecated [Deprecated]
private/utils.nim(7, 44) Warning: use StringTableRef instead; PStringTable is deprecated [Deprecated]
private/utils.nim(9, 47) Warning: use StringTableRef instead; PStringTable is deprecated [Deprecated]
private/utils.nim(17, 25) Warning: use ValueError instead; EInvalidValue is deprecated [Deprecated]
private/utils.nim(41, 43) Warning: use StringTableRef instead; PStringTable is deprecated [Deprecated]
private/utils.nim(49, 25) Warning: use ValueError instead; EInvalidValue is deprecated [Deprecated]
private/utils.nim(54, 31) Warning: use StringTableRef instead; PStringTable is deprecated [Deprecated]
private/utils.nim(63, 27) Warning: use ValueError instead; EInvalidValue is deprecated [Deprecated]