fix OpenAir Altitude parsing error :

     2000M ASFC -> 2000M MSL
     2000FT SFC -> SFC
     2000M SFC -> SFC

OpenAir test file :

********************************************************************************
*                                                                              *
*                         Special Use Airspace for tests                       *
*                                                                              *
********************************************************************************

AC CTR
AN CTR Test 1
AH UNL
AL SFC
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 2
AH FL115
AL GND
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 3 (Pieds)
AH 2000FT AGL
AL 1000F AGL
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 3 (Metres)
AH 2000M AGL
AL 1000M AGL
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 4 (Pieds)
AH 2000FT AMSL
AL 1000F AMSL
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 4 (Metres)
AH 2000M AMSL
AL 1000M AMSL
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 5 (Pieds)
AH 2000FT ASFC
AL 1000F ASFC
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 5 (Metres)
AH 2000M ASFC
AL 1000M ASFC
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 6 (Pieds)
AH 2000FT SFC
AL 1000F SFC
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 6 (Metres)
AH 2000M SFC
AL 1000M SFC
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 7 (Pieds)
AH 2000FT
AL 1000F
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 7 (Metres)
AH 2000M
AL 1000M
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

AC CTR
AN CTR Test 8 (Error)
AH 2000
AL 1000
DP 49:35:09 N 001:11:45 E
DP 49:31:10 N 001:22:43 E
DP 49:23:00 N 001:27:30 E
DP 49:16:58 N 001:13:09 E
DP 49:15:08 N 001:05:47 E
DP 49:22:11 N 000:53:40 E

********************************************************************************
Merge branch 'OpenAir' of git://github.com/brunotl/LK8000