Correct all eggs (#15906)

* "eg" is a misspelled "egg", "e.g." is "exempli gratia"
* Also, "ie" is "i.e.".

lib/system/jssys.nim

@@ -485,7 +485,7 @@ proc negInt64(a: int64): int64 {.compilerproc.} =
   result = a*(-1)
 
 proc nimFloatToString(a: float): cstring {.compilerproc.} =
-  ## ensures the result doesn't print like an integer, ie return 2.0, not 2
+  ## ensures the result doesn't print like an integer, i.e. return 2.0, not 2
   asm """
     function nimOnlyDigitsOrMinus(n) {
       return n.toString().match(/^-?\d+$/);

lib/system/strmantle.nim

@@ -113,7 +113,7 @@ when defined(nimHasInvariant):
 proc nimParseBiggestFloat(s: string, number: var BiggestFloat,
                           start = 0): int {.compilerproc.} =
   # This routine attempt to parse float that can parsed quickly.
-  # ie whose integer part can fit inside a 53bits integer.
+  # i.e. whose integer part can fit inside a 53bits integer.
   # their real exponent must also be <= 22. If the float doesn't follow
   # these restrictions, transform the float into this form:
   #  INTEGER * 10 ^ exponent and leave the work to standard `strtod()`.